ECS Journal of Solid State Science and Technology

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• The following article is Open access
  Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction Devices

  Hsiao-Hsuan Wan et al 2026 ECS J. Solid State Sci. Technol. 15 085002

  View article, Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction DevicesPDF, Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction DevicesOpen abstract

  Diamond-based devices are promising for operation in radiation environments due to their wide bandgap and strong atomic bonding. In this work, the effects of Co-60 gamma irradiation to a total dose of 1 Mrad on the electrical characteristics and carrier dynamics of diamond Schottky and indium-tin oxide (ITO)/boron doped diamond heterojunction rectifiers are investigated. The rectifiers were exposed to gamma radiation with photon energies of 1.17 and 1.33 MeV, where ionization dominates over displacement damage. The Schottky diodes exhibit minimal changes in both forward and reverse current characteristics after irradiation, indicating stable metal/diamond interfaces. In contrast, the heterojunction devices show a positive shift of forward IV around the diode turn-on voltage and an increased ideality factor, suggesting modification of charge accumulation in the ITO. The changes in electrical characteristics for both rectifiers are reversible by application of short forward current pulses during repeated measurement of the current–voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers under the irradiation conditions used in this study. Reverse current shows only minor variation for both types of rectifiers, confirming the absence of significant bulk leakage paths. Reverse recovery measurements reveal a reduction in recovery time after irradiation, attributed to decreased carrier lifetime and reduced stored charge due to radiation-induced traps. The extracted carrier concentration from the capacitance–voltage analysis changes only slightly from 1.23 × 10¹⁶ to 1.20 × 10¹⁶ cm⁻³ after irradiation confirming that gamma irradiation does not induce measurable degradation in bulk electrical properties under the irradiation conditions used in this study. While isolated Frenkel defects or other point defects may be generated during gamma irradiation, their concentration is evidently too low to produce measurable changes in carrier concentration or leakage current. The corresponding carrier removal rate is on the order of ∼0.1 cm⁻¹. This small variation indicates that gamma irradiation does not significantly affect the bulk carrier concentration in diamond. These results indicate that gamma irradiation primarily affects carrier dynamics and interface properties, while the bulk diamond remains largely unaffected. Thus, diamond-based rectifiers may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.

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  https://doi.org/10.1149/2162-8777/ae9593
• The following article is Open access
  Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS Applications

  Vincent Pares et al 2026 ECS J. Solid State Sci. Technol. 15 084003

  View article, Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS ApplicationsPDF, Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS ApplicationsOpen abstract

  The present work presents a 200 mm wafer-scale single step industrial Chemical Mechanical Polishing (CMP) process to polish in situ doped polysilicon using a commercial silica-based slurry. By tuning CMP operating conditions and pad conditioning, the surface roughness is reduced uniformly across the wafer down to Rq = 0.22 nm. The observed trends suggest that, within the investigated process window, slurry chemistry plays a role in achieving the lowest roughness, while pad conditioning strongly influences polishing uniformity. In particular, gentler conditioning parameters and less aggressive disk lowers nanoscale surface roughness and improves wafer-scale uniformity. A minimum material removal is required to reach the lowest roughness. Beyond this threshold, Rq remains stable and independent of additional removal. The same behavior is observed over four different ISDP film materials, regardless of the film thickness or post-deposition annealing. Hydrophobic direct bonding of a polished ISDP wafer to a monocrystalline silicon one, yielded defect free interface and high bond strength, demonstrating the potential of the ISDP CMP process to produce surfaces compatible with demanding wafer level packaging requirements.

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  Highlights

  • Achieved 0.22 nm RMS roughness uniformly on four in situ doped polysilicon films (thickness, anneal)

  • Single step CMP on 200 mm production tool using commercial silica slurry

  • Gentler pad conditioning improved nanoscale roughness and wafer scale uniformity

  • Only a few nanometers removal needed; beyond a threshold, roughness stayed stable

  • Final surface roughness meets hydrophobic direct bonding needs for MEMS wafer packaging

  https://doi.org/10.1149/2162-8777/ae72cd
• The following article is Open access
  High-Efficiency Novel Cu₃InSnS₅ Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy Harvesting

  Oussama Taleb Jlidi et al 2026 ECS J. Solid State Sci. Technol. 15 095001

  View article, High-Efficiency Novel Cu3InSnS5 Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy HarvestingPDF, High-Efficiency Novel Cu3InSnS5 Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy HarvestingOpen abstract

  This study presents a comprehensive numerical optimization of single and tandem photovoltaic cells utilizing novel Cu₃InSnS₅ colloidal quantum dots (CQDs) as absorbers. These quaternary CQDs have emerged as a compelling class of low-dimensional materials due to their tunable optoelectronic properties and compliance with the Restriction of Hazardous Substances (RoHS) directive. A multi-scale simulation framework is employed, combining the envelope function approximation to predict size-dependent quantum confinement effects, Rigorous Coupled-Wave Analysis (RCWA) for optical modeling, and the Solar Cell Capacitance Simulator (SCAPS-1D) for device-level electrical optimization. By systematically tuning the CQD radius, buffer layer, and absorber thickness, the optimized single-junction cell achieves a power conversion efficiency of 11.53% under standard AM1.5G illumination, significantly surpassing the current experimental benchmark of <0.1%. Furthermore, a tandem architecture is designed to minimize thermalization losses, yielding an impressive efficiency of 31.97% under AM1.5G. Under indoor LED illumination (1250 lx), the single and tandem cells attain efficiencies of 12.13% and 22.21%, respectively. These findings underscore the immense potential of Cu₃InSnS₅ CQDs for dual indoor/outdoor energy harvesting, particularly for powering low-light Internet of Things (IoT) devices.

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  https://doi.org/10.1149/2162-8777/ae9db8
• The following article is Open access
  A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-Up

  Han Cui and Shaofeng Kong 2026 ECS J. Solid State Sci. Technol. 15 033006

  View article, A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-UpPDF, A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-UpOpen abstract

  With the advancement of electric vehicle (EV) battery technologies, conventional lithium-ion batteries are approaching their theoretical energy density limits while facing persistent safety concerns. All-solid-state batteries (ASSBs) offer a pathway toward higher energy density and enhanced safety. This review focuses on the fabrication and manufacturing processes of ASSBs, explicitly bridging laboratory-scale research methods with emerging industrial-scale production routes. Emphasis is placed on material systems, scalable processing strategies, manufacturing bottlenecks, and industrial roadmaps.

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  https://doi.org/10.1149/2162-8777/ae5451
• The following article is Open access
  Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and Applications

  Alain E. Kaloyeros et al 2020 ECS J. Solid State Sci. Technol. 9 063006

  View article, Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and ApplicationsPDF, Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and ApplicationsOpen abstract

  Accelerating interest in silicon nitride thin film material system continues in both academic and industrial communities due to its highly desirable physical, chemical, and electrical properties and the potential to enable new device technologies. As considered here, the silicon nitride material system encompasses both non-hydrogenated (SiN_x) and hydrogenated (SiN_x:H) silicon nitride, as well as silicon nitride-rich films, defined as SiN_x with C inclusion, in both non-hydrogenated (SiN_x(C)) and hydrogenated (SiN_x:H(C)) forms. Due to the extremely high level of interest in these materials, this article is intended as a follow-up to the authors’ earlier publication [A. E. Kaloyeros, F. A. Jové, J. Goff, B. Arkles, Silicon nitride and silicon nitride-rich thin film technologies: trends in deposition techniques and related applications, ECS J. Solid State Sci. Technol., 6, 691 (2017)] that summarized silicon nitride research and development (R&D) trends through the end of 2016. In this survey, emphasis is placed on cutting-edge achievements and innovations from 2017 through 2019 in Si and N source chemistries, vapor phase growth processes, film properties, and emerging applications, particularly in heterodevice areas including sensors, biointerfaces and photonics.

  https://doi.org/10.1149/2162-8777/aba447
• Corrigendum: Graphene Nano-Engineered Plasma-Tailored Dielectric Interfaced (GNPTD) Field-Effect Transistor for Ultrasensitive Detection of Breast Cancer Biomarkers [ECS J. Solid State Sci. Technol., 15, 053007 (2026)]

  Priyanka Yadav et al 2026 ECS J. Solid State Sci. Technol. 15 089002

  View article, Corrigendum: Graphene Nano-Engineered Plasma-Tailored Dielectric Interfaced (GNPTD) Field-Effect Transistor for Ultrasensitive Detection of Breast Cancer Biomarkers [ECS J. Solid State Sci. Technol., 15, 053007 (2026)]PDF, Corrigendum: Graphene Nano-Engineered Plasma-Tailored Dielectric Interfaced (GNPTD) Field-Effect Transistor for Ultrasensitive Detection of Breast Cancer Biomarkers [ECS J. Solid State Sci. Technol., 15, 053007 (2026)]
  https://doi.org/10.1149/2162-8777/ae8938
• The following article is Open access
  Void Formation Mechanism Related to Particles During Wafer-to-Wafer Direct Bonding

  F. Nagano et al 2022 ECS J. Solid State Sci. Technol. 11 063012

  View article, Void Formation Mechanism Related to Particles During Wafer-to-Wafer Direct BondingPDF, Void Formation Mechanism Related to Particles During Wafer-to-Wafer Direct BondingOpen abstract

  Achieving a void-free bonding interface is an important requirement for the wafer-to-wafer direct bonding process. The two main potential mechanisms for void formation at the interface are (i) void formation induced by gas, such as condensation by-products caused by the bonding process or outgassing of trapped precursors, and (ii) void formation induced by physical obstacles, such as particles. In this work, emphasis is on the latter process. Particles were intentionally deposited on the wafer prior to bonding to study the kinetics of the physical void formation process. Void formations induced by particles deposited on different dielectrics bonding materials were analyzed using scanning acoustic microscopy and image software. The void formation mechanism is then discussed along with the wafer bonding dynamics at room temperature.

  https://doi.org/10.1149/2162-8777/ac7662
• The following article is Open access
  Review—Ionizing Radiation Damage Effects on GaN Devices

  S. J. Pearton et al 2016 ECS J. Solid State Sci. Technol. 5 Q35

  View article, Review—Ionizing Radiation Damage Effects on GaN DevicesPDF, Review—Ionizing Radiation Damage Effects on GaN DevicesOpen abstract

  Gallium Nitride based high electron mobility transistors (HEMTs) are attractive for use in high power and high frequency applications, with higher breakdown voltages and two dimensional electron gas (2DEG) density compared to their GaAs counterparts. Specific applications for nitride HEMTs include air, land and satellite based communications and phased array radar. Highly efficient GaN-based blue light emitting diodes (LEDs) employ AlGaN and InGaN alloys with different compositions integrated into heterojunctions and quantum wells. The realization of these blue LEDs has led to white light sources, in which a blue LED is used to excite a phosphor material; light is then emitted in the yellow spectral range, which, combined with the blue light, appears as white. Alternatively, multiple LEDs of red, green and blue can be used together. Both of these technologies are used in high-efficiency white electroluminescent light sources. These light sources are efficient and long-lived and are therefore replacing incandescent and fluorescent lamps for general lighting purposes. Since lighting represents 20–30% of electrical energy consumption, and because GaN white light LEDs require ten times less energy than ordinary light bulbs, the use of efficient blue LEDs leads to significant energy savings. GaN-based devices are more radiation hard than their Si and GaAs counterparts due to the high bond strength in III-nitride materials. The response of GaN to radiation damage is a function of radiation type, dose and energy, as well as the carrier density, impurity content and dislocation density in the GaN. The latter can act as sinks for created defects and parameters such as the carrier removal rate due to trapping of carriers into radiation-induced defects depends on the crystal growth method used to grow the GaN layers. The growth method has a clear effect on radiation response beyond the carrier type and radiation source. We review data on the radiation resistance of AlGaN/GaN and InAlN/GaN HEMTs and GaN–based LEDs to different types of ionizing radiation, and discuss ion stopping mechanisms. The primary energy levels introduced by different forms of radiation, carrier removal rates and role of existing defects in GaN are discussed. The carrier removal rates are a function of initial carrier concentration and dose but not of dose rate or hydrogen concentration in the nitride material grown by Metal Organic Chemical Vapor Deposition. Proton and electron irradiation damage in HEMTs creates positive threshold voltage shifts due to a decrease in the two dimensional electron gas concentration resulting from electron trapping at defect sites, as well as a decrease in carrier mobility and degradation of drain current and transconductance. State-of-art simulators now provide accurate predictions for the observed changes in radiation-damaged HEMT performance. Neutron irradiation creates more extended damage regions and at high doses leads to Fermi level pinning while ⁶⁰Co γ-ray irradiation leads to much smaller changes in HEMT drain current relative to the other forms of radiation. In InGaN/GaN blue LEDs irradiated with protons at fluences near 10¹⁴ cm⁻² or electrons at fluences near 10¹⁶ cm⁻², both current-voltage and light output-current characteristics are degraded with increasing proton dose. The optical performance of the LEDs is more sensitive to the proton or electron irradiation than that of the corresponding electrical performances.

  https://doi.org/10.1149/2.0251602jss
• The following article is Open access
  Origin and Innovations of CMP Slurry

  Hitoshi Morinaga 2024 ECS J. Solid State Sci. Technol. 13 074006

  View article, Origin and Innovations of CMP SlurryPDF, Origin and Innovations of CMP SlurryOpen abstract

  This paper reviews how today’s CMP (Chemical Mechanical Polishing) slurries have been innovated and explores ideas for driving further evolution. In early semiconductor polishing, Mechanical Polishing was used, focusing on controlling abrasive particle sizes, leading to the use of alumina abrasives via wet classification. As materials shifted from germanium to silicon and applications transitioned from radios to integrated circuits, research was conducted on the material and size of abrasives to improve polishing accuracy, and silica was finally adopted. Subsequently, in pursuit of higher purity, ultrapure colloidal silica using organic raw materials was introduced in 1985 and became the standard in current semiconductor CMP. The first report on CMP dates back to Schmidt’s 1962 paper. Although the report was based on visual inspection, the approach was validated to be reasonable with today’s inspection technology. CMP achieved further defect reduction by integrating with Clean Technology. Throughout its history, polishing consistently pursued uniform action on surfaces, driving contaminant reduction, and occasionally achieving significant breakthroughs through the combination of diverse technologies. Innovations are born when disparate technologies, evolving independently until a certain point, interact and combine according to market needs.

  https://doi.org/10.1149/2162-8777/ad5fb6
• The following article is Open access
  TCAD Simulation Models, Parameters, and Methodologies for β-Ga₂O₃ Power Devices

  Hiu Yung Wong 2023 ECS J. Solid State Sci. Technol. 12 055002

  View article, TCAD Simulation Models, Parameters, and Methodologies for β-Ga2O3 Power DevicesPDF, TCAD Simulation Models, Parameters, and Methodologies for β-Ga2O3 Power DevicesOpen abstract

  β-Ga₂O₃ is an emerging material and has the potential to revolutionize power electronics due to its ultra-wide-bandgap (UWBG) and lower native substrate cost compared to Silicon Carbide and Gallium Nitride. Since β-Ga₂O₃ technology is still not mature, experimental study of β-Ga₂O₃ is difficult and expensive. Technology-Computer-Aided Design (TCAD) is thus a cost-effective way to study the potentials and limitations of β-Ga₂O₃ devices. In this paper, TCAD parameters calibrated to experiments are presented. They are used to perform the simulations in heterojunction p-NiO/n-Ga₂O₃ diode, Schottky diode, and normally-off Ga₂O₃ vertical FinFET. Besides the current-voltage (I-V) simulations, breakdown, capacitance-voltage (C-V), and short-circuit ruggedness simulations with robust setups are discussed. TCAD Sentaurus is used in the simulations but the methodologies can be applied in other simulators easily. This paves the road to performing a holistic study of β-Ga₂O₃ devices using TCAD.

  https://doi.org/10.1149/2162-8777/accfbe

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• The following article is Open access
  Plasma Etching of SiO₂ Using C=O-Containing Fluorocarbons with Low Global Warming Potentials

  Minuk Kim et al 2026 ECS J. Solid State Sci. Technol. 15 091001

  View article, Plasma Etching of SiO2 Using C=O-Containing Fluorocarbons with Low Global Warming PotentialsPDF, Plasma Etching of SiO2 Using C=O-Containing Fluorocarbons with Low Global Warming PotentialsOpen abstract

  SiO₂ was etched in plasmas of C=O-containing fluorocarbon compounds with global warming potentials (GWPs) of unity or lower, such as trifluoroacetyl fluoride (C₂F₄O), octafluoro-2-butanone (C₄F₈O), and heptafluoroisopropyl trifluoromethyl ketone (C₅F₁₀O), and their etch characteristics were compared with those of CHF₃, a hydrofluorocarbon with a high GWP of 14 600, in an inductively coupled plasma system. The etch rate was the lowest in the C₂F₄O/Ar plasma, whereas the etch rates in the C₄F₈O/Ar and C₅F₁₀O/Ar plasmas were comparable to that in the CHF₃/Ar plasma. X-ray photoelectron spectroscopy revealed that the steady-state fluorocarbon films formed on SiO₂ were thinner than 4 Å in all plasmas, indicating that the etch-rate trend was governed mainly by radical populations rather than film-thickness effects. Optical emission spectroscopy showed that the apparent total amount of CF₂, CF, and F radicals was lowest in C₂F₄O/Ar and similar in C₄F₈O/Ar, C₅F₁₀O/Ar, and CHF₃/Ar. The radical populations were rationalized by the bond dissociation energies and molecular structures of the discharge gases. These results demonstrate that C₄F₈O and C₅F₁₀O are promising environmentally sustainable alternatives to high-GWP CHF₃ for plasma etching of SiO₂.

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  Research Highlights

  • SiO₂ was etched in plasmas of C₂F₄O, C₄F₈O, and C₅F₁₀O with GWPs of unity or lower.

  • C₄F₈O/Ar and C₅F₁₀O/Ar plasmas etch SiO₂ as fast as high-GWP CHF₃/Ar plasma.

  • Etch rates were governed by CF₂, CF, and F radical populations measured by OES.

  • Bond dissociation energies and molecular structures explain radical generation.

  • GWP of the etch gas is reduced from 14 600 to below unity without tool changes.

  https://doi.org/10.1149/2162-8777/aea250
• Dielectric Relaxation, Molecular Interactions and Structural Characteristics of PVA/Aloe Vera Bio-Composites

  Pooja Saxena and Prashant Shukla 2026 ECS J. Solid State Sci. Technol. 15 093003

  View article, Dielectric Relaxation, Molecular Interactions and Structural Characteristics of PVA/Aloe Vera Bio-CompositesPDF, Dielectric Relaxation, Molecular Interactions and Structural Characteristics of PVA/Aloe Vera Bio-CompositesOpen abstract

  Plant-based natural aloe Vera gel-incorporated PVA biocomposite films with varying concentrations of aloe Vera gel were prepared by the solution-grown technique. The objective of this study was to examine the structural modifications and to investigate the thermal, electrical, and dielectric behavior of the biocomposite film. SEM reveals slight morphological modifications, with interfacial adhesion observed between the polymer blend matrix and aloe vera gel. Enhanced intermolecular hydrogen bonding interactions were observed within the biocomposite network, but covalent chemical grafting remains absent, as confirmed by FTIR. DSC graphs revealed the systematic variation in glass transition temperature, enhanced chain mobility, and improved compatibility among the components. TGA was performed to examine the thermal stability and decomposition behavior of the biocomposite. The study shows the degradation behavior in multiple stages, with improved thermal stability of the film. Dielectric spectroscopy graphs show the dielectric relaxation curve at different frequencies. The shift in the relaxation peak was observed at higher concentrations of aloe Vera gel in the polymer biocomposite. This suggests an enhanced dipolar and interfacial polarization mechanism. Charge storage characteristics and dielectric response were significantly improved by the addition of aloe Vera gel into the pure PVA polymer matrix. The produced eco-friendly biocomposite films have great potential for use in flexible dielectric materials, electret devices, low-power electronics, and sustainable sensing systems.

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  https://doi.org/10.1149/2162-8777/aea026
• Anodic Oxidation Behavior and Stepwise Voltage-Regulated Electrochemical Mechanical Polishing of 4H-SiC

  Haonan Zhao et al 2026 ECS J. Solid State Sci. Technol. 15 094001

  View article, Anodic Oxidation Behavior and Stepwise Voltage-Regulated Electrochemical Mechanical Polishing of 4H-SiCPDF, Anodic Oxidation Behavior and Stepwise Voltage-Regulated Electrochemical Mechanical Polishing of 4H-SiCOpen abstract

  Electrochemical mechanical polishing (ECMP) is a promising technique for achieving efficient and low-damage planarization of 4H-SiC. However, the difficulty in balancing electrochemical oxidation and mechanical removal during ECMP limits both processing efficiency and surface quality. In this study, the anodic oxidation behavior of 4H-SiC in NaCl solution under different voltages was investigated through electrochemical experiments. Equivalent circuit modeling and fitting analysis clarified the evolution of oxide-layer growth, passivation, and breakdown. Based on these findings, a periodic stepwise voltage strategy was proposed for rough and fine polishing to dynamically regulate the balance between electrochemical oxidation and mechanical removal. Mechanistically, the oxide layer was mechanically removed by CeO₂ abrasives, while periodic voltage switching suppressed excessive oxidation and repeated local oxide-layer breakdown. The process achieved material removal rate (MRR) of 1.497 μm h⁻¹ and 0.751 μm h⁻¹ during rough and fine polishing, respectively, and reduced the surface roughness (Ra) from 5.531 nm to 0.587 nm within 1 h. This work provides a strategy for coordinating electrochemical oxidation and mechanical removal in 4H-SiC ECMP.

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  Highlights

  • Voltage-dependent anodic oxidation behavior and oxide-layer evolution of 4H-SiC in NaCl solution were systematically investigated, revealing the transition from stable passivation to local breakdown under increasing voltages

  • Equivalent circuit models and impedance formulas were established to quantitatively describe oxide-layer growth, charge transfer, and interfacial instability during 4H-SiC anodic oxidation.

  • A periodic stepwise voltage-regulated ECMP process was proposed to dynamically match oxide-layer formation with mechanical removal, achieving a smooth 4H-SiC surface with Ra = 0.587 nm.

  https://doi.org/10.1149/2162-8777/aea18a
• Device-Circuit Co-Design Investigation of a Structurally Engineered 7 nm InGaAs-SOI Complementary FinFET for Wide-Temperature CMOS Operation

  Jitendra Gurjar et al 2026 ECS J. Solid State Sci. Technol. 15 095003

  View article, Device-Circuit Co-Design Investigation of a Structurally Engineered 7 nm InGaAs-SOI Complementary FinFET for Wide-Temperature CMOS OperationPDF, Device-Circuit Co-Design Investigation of a Structurally Engineered 7 nm InGaAs-SOI Complementary FinFET for Wide-Temperature CMOS OperationOpen abstract

  In this work, we report a structurally optimized design of 7 nm InGaAs-SOI complementary FinFET, and demonstrate thermal reliability of InGaAs-based logic device and circuit-level behavior over a wide temperature range of $\sim$200–$\sim$700 K. The proposed 7 nm InGaAs–SOI FinFET with optimized fin architecture achieves Vth values of 0.50 and 0.60 V for the n-type and p-type FinFETs, respectively, with an exceptional ON/OFF current ratio of $6.21\times10^{10}$, subthreshold swing (SS) of 67.44 mV dec$^{-1}$, and drain-induced barrier lowering (DIBL) of 59.20 mV V$^{-1}$. It is observed that the InGaAs–SOI FinFET device exhibits strong self-heating characteristics and superior short-channel immunity at elevated operating temperatures compared to conventional Si CMOS FinFETs and wide-bandgap technologies such as SiC. Furthermore, to mitigate the inherent imbalance at the circuit level, an asymmetric complementary inverter is designed using a 4:1 pMOS-to-nMOS Fin ratio to offset the electron–hole mobility disparity. The optimized binary inverter sustains reliable switching operation and exhibits improved voltage gain with maintaining positive noise margins up to 700 K at a low supply voltage of 1.5 V. These findings highlight the promise of InGaAs-SOI CMOS FinFETs for high-speed logic applications operating in elevated-temperature environments, such as defense and space systems.

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  https://doi.org/10.1149/2162-8777/aea18b
• Electrocatalytic Hydrogen Evolution Performance of Nitrogen-Rich Porous Carbon Coupled with Cobalt -Doped MoS₂

  Ning Pei et al 2026 ECS J. Solid State Sci. Technol. 15 093002

  View article, Electrocatalytic Hydrogen Evolution Performance of Nitrogen-Rich Porous Carbon Coupled with Cobalt -Doped MoS2PDF, Electrocatalytic Hydrogen Evolution Performance of Nitrogen-Rich Porous Carbon Coupled with Cobalt -Doped MoS2Open abstract

  A Co–doped MoS₂/nitrogen-rich porous carbon composite (Co–MoS₂@CN) was prepared by KOH-assisted activation and hydrothermal synthesis for hydrogen evolution reaction (HER) electrocatalysis. Characterization confirmed that the porous CN support improved MoS₂ dispersion and active-site exposure, while Co incorporation enhanced interfacial charge transfer. At the optimized Mo ratio of 1:2, CN content of 0.3 g, and Co concentration of 0.7 mM, Co–MoS₂@CN required overpotentials of 182 and 254 mV to reach 10 and 25 mA cm⁻², respectively, in 0.5 M H₂SO₄. The catalyst exhibited a Tafel slope of 73.8 mV dec⁻¹, a double-layer capacitance of 15.69 mF cm⁻², and a charge-transfer resistance of 228 Ω. These results demonstrate that coupling Co doping with nitrogen-rich porous carbon is an effective strategy for improving the HER performance of MoS₂-based electrocatalysts.

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  Highlights

  1.A nitrogen-rich porous carbon supported Co–MoS₂ composite electrocatalyst was rationally designed for enhanced HER performance.

  2.Co doping induces lattice distortion and partial 2H-to-1T phase transition, improving conductivity and intrinsic catalytic activity.

  3.The porous carbon framework suppresses MoS₂ aggregation and provides abundant active sites with accelerated charge transfer.

  4.The optimized Co–MoS₂@CN catalyst achieves a low overpotential of 229 mV at 10 mA cm⁻² in 0.5 M H₂SO₄.

  5.A synergistic strategy combining heteroatom doping and interface engineering is demonstrated for efficient non-noble HER catalysts.

  https://doi.org/10.1149/2162-8777/aea251

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• Influence of Complexing Agents on the Material Removal Rate Selectivity in CMP for Copper Interconnects

  Jiaji Geng et al 2026 ECS J. Solid State Sci. Technol. 15 064003

  View article, Influence of Complexing Agents on the Material Removal Rate Selectivity in CMP for Copper InterconnectsPDF, Influence of Complexing Agents on the Material Removal Rate Selectivity in CMP for Copper InterconnectsOpen abstract

  Copper (Cu) interconnects are extensively employed in the manufacturing of integrated circuits. During the chemical mechanical polishing (CMP) process of these interconnects, precise control over the material removal selectivity between copper and barrier layers, such as tantalum/tantalum nitride (Ta/TaN), cobalt (Co), and ruthenium (Ru), is essential. As a critical component in CMP slurries, complexing agents play a direct role in regulating this selectivity by forming coordination bonds with copper and barrier-layer metals. This paper provides a systematic review of the mechanisms of commonly used complexing agents in CMP, classifying them into five categories: carboxylic acids, amines, organic acids, inorganic salts, and macromolecular polymer complexing agents. It focuses on elucidating their respective action mechanisms and current limitations in the removal of copper and barrier-layer metals. The review aims to offer valuable insights for future research and technological advances in related fields, as well as a theoretical foundation for achieving more efficient and controllable CMP processes.

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  https://doi.org/10.1149/2162-8777/ae70a8
• Evolution of Emerging Transistor Technologies Toward Quantum Devices in Nanoelectronics

  M. Balasubrahmanyam et al 2026 ECS J. Solid State Sci. Technol. 15 055005

  View article, Evolution of Emerging Transistor Technologies Toward Quantum Devices in NanoelectronicsPDF, Evolution of Emerging Transistor Technologies Toward Quantum Devices in NanoelectronicsOpen abstract

  Transistor Technology plays a crucial role in human life. The aim is to increase the number of applications and increase speed in a single Integrated Circuit (IC) of Transistor Technology. This paper reviews the conventional transistor devices (Planar MOSFET, MESFET, DGMOSFET, DGMOSFET with Dual Material, and DGMOSFET with High-k Materials), modern transistor devices (FinFET and SOI FinFET), and advanced transistor devices (GAAFET (Gate All Around Nanosheet FET, Gate All around Nanowire FET and Tree FET). Different aspects, such as Drain Induced Barrier Leakage (DIBL), Leakage Current, Short Channel Effects (SCE), and Subthreshold Swing (SS), influence the performance of FETs. A comparison study shows that the Nanosheet Field Effect Transistor (NSFET) is the best transistor device in the semiconductor industry due to its low power performance, and also provides low parasitic capacitance, low temperature sensitivity, better electrostatic control, higher switching capacity, and good considerable scaling. The review also explores the development of next-generation transistor architectures such as Forksheet FETs, Complementary FETs, Vertical Transport FETs, Quantum Dot Transistors, Single-Electron Transistors, and Qubit Devices, which are among the most promising candidates under active research and are being considered as potential replacements for nanosheet FETs.

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  Highlights

  • This paper reviews the conventional transistor devices (Planar MOSFET, DGMOSFET, etc), modern transistor devices (FinFET and SOI FinFET), and advanced transistor devices (GAAFET (Gate All Around Nanosheet FET, Gate All around Nanowire FET and Tree FET).

  • A comparison study shows that the Nanosheet Field Effect Transistor (NSFET) is the best transistor device in the semiconductor industry due to its low power performance, and also provides low parasitic capacitance, better electrostatic control, and good considerable scaling.

  • The review also explores the development of next-generation transistor architectures such as Forksheet FETs, Complementary FETs, Vertical Transport FETs, Quantum Dot Transistors, Single-Electron Transistors, and Qubit Devices, which are among the most promising candidates under active research and are being considered as potential replacements for nanosheet FETs.

  https://doi.org/10.1149/2162-8777/ae6a6c
• The following article is Open access
  A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-Up

  Han Cui and Shaofeng Kong 2026 ECS J. Solid State Sci. Technol. 15 033006

  View article, A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-UpPDF, A Review on the Fabrication and Manufacturing Processes of All-Solid-State Batteries From Laboratory Research to Industrial Scale-UpOpen abstract

  With the advancement of electric vehicle (EV) battery technologies, conventional lithium-ion batteries are approaching their theoretical energy density limits while facing persistent safety concerns. All-solid-state batteries (ASSBs) offer a pathway toward higher energy density and enhanced safety. This review focuses on the fabrication and manufacturing processes of ASSBs, explicitly bridging laboratory-scale research methods with emerging industrial-scale production routes. Emphasis is placed on material systems, scalable processing strategies, manufacturing bottlenecks, and industrial roadmaps.

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  https://doi.org/10.1149/2162-8777/ae5451
• Graphene as a Biomedical Material: Potentials and Perspectives

  Priyanka Mahajan et al 2026 ECS J. Solid State Sci. Technol. 15 011002

  View article, Graphene as a Biomedical Material: Potentials and PerspectivesPDF, Graphene as a Biomedical Material: Potentials and PerspectivesOpen abstract

  Biomedical procedures needed to be upgraded with time through various innovative techniques in order to enhance its efficacy. Graphene’s transformative potential in biomedicine owing to its unique physicochemical properties provides innovative platform in this regard. The current review begins with highlights on key attributes of graphene such as biocompatibility, surface functionalization potential, mechanical strength, and electrical/thermal conductivity. Further emphasis has been given to the graphene’s diverse roles, including nanocarriers for drug delivery, stimuli-responsive and targeted therapeutic strategies, biosensors for biomarker detection and their integration into wearable devices, and significant contributions to tissue engineering as well as regenerative medicine through scaffolds. Besides, its applications in bioimaging (MRI, fluorescence) and photothermal/photodynamic therapies are also discussed. Later part of review involves in vitro/in vivo biocompatibility and dose-dependent toxicity of graphene. Conclusively, the major challenges obstructing graphene-derivatives in biomedical applications are highlighted along with possible measures. Integration with emerging trends like AI and ML- empowered devices can underscore graphene’s promising role in next-generation biomedical platforms.

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  https://doi.org/10.1149/2162-8777/ae31ab
• Nanomaterial-Engineered Solid-State Sensors: Advances in Metal Oxides, MXenes, and Sustainable Electronics

  Prachi Palta et al 2025 ECS J. Solid State Sci. Technol. 14 127002

  View article, Nanomaterial-Engineered Solid-State Sensors: Advances in Metal Oxides, MXenes, and Sustainable ElectronicsPDF, Nanomaterial-Engineered Solid-State Sensors: Advances in Metal Oxides, MXenes, and Sustainable ElectronicsOpen abstract

  Recent developments in nano-materials have re-architected the frontiers of solid-state sensor design, enabling high sensitivity, selectivity, and sustainability across a broad spectrum of real-world applications. This review summarises the advances in nanomaterial-engineered sensors, including the connection between material structure and functional mechanisms, as well as the device’s performance. Doped metal-oxide semiconductors (SnO₂ or ZnO, or WO₃) or polyoxometalates or MXenes exhibit an improved speed of charge transfer, low temperatures, and selectivity. Hydrophilic polymers, biocomposites and MXene hybrid sensors based on impedance and ionic humidity are flexible, fast-reactive and self-powered. Piezoelectric and photoacoustic transduction, based on ferroelectric ceramics, PVDF, and bio-based polymers such as PLA, chitosan, and cellulose, provides a platform for sustainable and energy-harvesting wearable devices and implants. The combination of electrochemical materials and biodegradable materials also enhances environmentally friendly sensor technologies. Multimodal sensing is adopting new architectures developed using adaptive calibration and intelligent data interpretation based on new artificial intelligence. As observed in the review, the compositional tuning, heterostructuring, and nanoscale morphology are used to control the science of bridge materials and the engineering of functional devices. The vision for this area is to develop fully autonomous, power-driven, and recyclable sensor ecosystems that can seamlessly integrate into Internet of Things (IoT) networks, enabling continuous monitoring of the environment, health, and industrial status with minimal human intervention and environmental impact. Lastly, the existing challenges, such as interference from humidity, signal drift, and the possibility of large-scale manufacturability, are not only documented but also addressed through the opportunities presented by multifunctional sensor systems, autonomous sensor systems, and recyclable sensor systems of the future. Future developmental trends include the integration of machine learning algorithms with multimodal sensor arrays to provide real-time adaptive analytics, the development of biodegradable and bioresorbable platforms for transient implantable diagnostics, and the development of flexible, skin-conformal architectures for precision medicine and personalized wearable health monitoring. This comprehensive evaluation offers a unique perspective on how nanomaterial-engineered solid-state sensors can be utilized to support the development of next-generation, sustainable, and intelligent technologies.

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  https://doi.org/10.1149/2162-8777/ae2c1c

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• The following article is Open access
  Editors’ Choice—Structural, Electrical, and Luminescent Properties of Orthorhombic κ-Ga₂O₃ Grown by Epitaxial Lateral Overgrowth

  V. I. Nikolaev et al 2023 ECS J. Solid State Sci. Technol. 12 115001

  View article, Editors’ Choice—Structural, Electrical, and Luminescent Properties of Orthorhombic κ-Ga2O3 Grown by Epitaxial Lateral OvergrowthPDF, Editors’ Choice—Structural, Electrical, and Luminescent Properties of Orthorhombic κ-Ga2O3 Grown by Epitaxial Lateral OvergrowthOpen abstract

  The properties of orthorhombic κ-Ga₂O₃ films grown by Epitaxial Lateral Overgrowth (ELOG) were studied by Scanning Transmission Electron Microscopy (STEM), X-ray diffraction, capacitance-voltage profiling, Microcathodoluminescence (MCL) spectroscopy and imaging. ELOG mask was formed by deposition of SiO₂ stripes on TiO₂ buffer prepared on basal plane sapphire, with the stripes going along the [11$\mathop{2}\limits^{\unicode{x00305}}$0] direction of sapphire. κ-Ga₂O₃ ELOG growth was performed using Halide Vapor Phase Epitaxy (HVPE), with ELOG wing of the structure formed by lateral overgrowth over the 20 μm-wide SiO₂ stripes, while growth in between the stripes proceeded initially by vertical growth in the 5-μm-wide windows. TEM analysis showed that the material in the windows comprised 120^o rotational nanodomains typical of κ-Ga₂O₃, while, in the wing regions, the material was single-domain monocrystalline. The films were conducting, with the net donor density close to 10¹³ cm⁻³. The data suggested the material in the windows have much higher resistance than in the wings. MCL spectra and imaging revealed much higher density of nonradiative recombination centers in the windows than in the wings.

  https://doi.org/10.1149/2162-8777/ad0888
• The following article is Open access
  Editors’ Choice—Atomic Layer Etching of Tungsten Disulfide Using Remote Plasma-Induced Oxidation and Wet Etching

  Younghyun You et al 2023 ECS J. Solid State Sci. Technol. 12 075009

  View article, Editors’ Choice—Atomic Layer Etching of Tungsten Disulfide Using Remote Plasma-Induced Oxidation and Wet EtchingPDF, Editors’ Choice—Atomic Layer Etching of Tungsten Disulfide Using Remote Plasma-Induced Oxidation and Wet EtchingOpen abstract

  WS₂ is an emerging semiconductor with potential applications in next-generation device architecture owing to its excellent electrical and physical properties. However, the presence of inevitable surface contaminants and oxide layers limits the performance of WS₂-based field-effect transistors (FETs); therefore, novel methods are required to restore the pristine WS₂ surface. In this study, the thickness of a WS₂ layer was adjusted and its surface was restored to a pristine state by fabricating a recessed-channel structure through a combination of self-limiting remote plasma oxidation and KOH solution etching processes. The reaction between the KOH solution and WO_X enabled layer-by-layer thickness control as the topmost oxide layer was selectively removed during the wet-etching process. The thickness of the WS₂ layer decreased linearly with the number of recess cycles, and the vertical etch rate was estimated to be approximately 0.65 nm cycle⁻¹. Micro-Raman spectroscopy and high-resolution transmission electron microscopy revealed that the layer-by-layer etching process had a nominal effect on the crystallinity of the underlying WS₂ channel. Finally, the pristine state was recovered by removing ambient molecules and oxide layers from the surface of the WS₂ channel, which resulted in a high-performance FET with a current on/off ratio greater than 10⁶. This method, which provides a facile approach to restoring the pristine surfaces of transition-metal dichalcogenide (TMDC) semiconductors with precise thickness control, has potential applications in various fields such as TMDC-based (opto)electronic and sensor devices.

  https://doi.org/10.1149/2162-8777/ace6d5
• The following article is Open access
  Editors’ Choice—Thin Film Transistor Response in the THz Range

  M. S. Shur et al 2023 ECS J. Solid State Sci. Technol. 12 035008

  View article, Editors’ Choice—Thin Film Transistor Response in the THz RangePDF, Editors’ Choice—Thin Film Transistor Response in the THz RangeOpen abstract

  Novel metal oxide materials such as InGaZnO (IGZO), ZnO, SnO, and In₂O₃ and improved fabrication processes dramatically enhanced the achieved and projected thin film transistor (TFT) performance. The record values of the effective field-effect mobility of Metal Oxide TFT (MOTFT) materials have approached 150 cm²/Vs. We report on an improved compact TFT model based on three models: the RPI TFT model, the unified charge control model (UCCM), and the multi-segment TFT compact model. This improved model accounts for a non-exponential slope in the subthreshold regime by introducing a varying subthreshold slope and accounts for non-trivial capacitance dependence on the gate bias, and parasitic impedances. The analysis of the TFT response using this model and the analytical calculations showed that TFTs could have a significant response to impinging THz and sub-THz radiation. Using a complementary inverter and the phase-matched THz signal feeding significantly improves the detection sensitivity.

  https://doi.org/10.1149/2162-8777/acc20d
• The following article is Open access
  Editors’ Choice—Vibrational Properties of Oxygen-Hydrogen Centers in H⁺- and D⁺-Implanted Ga₂O₃

  Amanda Portoff et al 2020 ECS J. Solid State Sci. Technol. 9 125006

  View article, Editors’ Choice—Vibrational Properties of Oxygen-Hydrogen Centers in H+- and D+-Implanted Ga2O3PDF, Editors’ Choice—Vibrational Properties of Oxygen-Hydrogen Centers in H+- and D+-Implanted Ga2O3Open abstract

  The ion implantation of H⁺ and D⁺ into Ga₂O₃ produces several O–H and O–D centers that have been investigated by vibrational spectroscopy. These defects include the dominant V_Ga(1)-2H and V_Ga(1)-2D centers studied previously along with additional defects that can be converted into this structure by thermal annealing. The polarization dependence of the spectra has also been analyzed to determine the directions of the transition moments of the defects and to provide information about defect structure. Our experimental results show that the implantation of H⁺ (or D⁺) into Ga₂O₃ produces two classes of defects with different polarization properties. Theory finds that these O–H (or O–D) centers are based on two shifted configurations of a Ga(1) vacancy that trap H (or D) atom(s). The interaction of V_Ga(1)-nD centers with other defects in the implanted samples has also been investigated to help explain the number of O–D lines seen and their reactions upon annealing. Hydrogenated divacancy V_Ga(1)-V_O centers have been considered as an example.

  https://doi.org/10.1149/2162-8777/abd458
• The following article is Open access
  Editors’ Choice—Precipitation of Suboxides in Silicon, their Role in Gettering of Copper Impurities and Carrier Recombination

  G. Kissinger et al 2020 ECS J. Solid State Sci. Technol. 9 064002

  View article, Editors’ Choice—Precipitation of Suboxides in Silicon, their Role in Gettering of Copper Impurities and Carrier RecombinationPDF, Editors’ Choice—Precipitation of Suboxides in Silicon, their Role in Gettering of Copper Impurities and Carrier RecombinationOpen abstract

  This paper describes a theoretical investigation of the phase composition of oxide precipitates and the corresponding emission of self-interstitials at the minimum of the free energy and their evolution with increasing number of oxygen atoms in the precipitates. The results can explain the compositional evolution of oxide precipitates and the role of self-interstitials therein. The formation of suboxides at the edges of SiO₂ precipitates after reaching a critical size can explain several phenomena like gettering of Cu by segregation to the suboxide region and lifetime reduction by recombination of minority carriers in the suboxide. It provides an alternative explanation, based on minimized free energy, to the theory of strained and unstrained plates. A second emphasis was payed to the evolution of the morphology of oxide precipitates. Based on the comparison with results from scanning transmission electron microscopy the sequence of morphology evolution of oxide precipitates was deduced. It turned out that it is opposite to the sequence assumed until now.

  https://doi.org/10.1149/2162-8777/aba0ce

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• Hydrothermal Synthesis and Characterization of Pure ZnO Nanoparticles for Energy Storage and Electromagnetic Interference Shielding Applications

  L et al 

  View accepted manuscript, Hydrothermal Synthesis and Characterization of Pure ZnO Nanoparticles for Energy Storage and Electromagnetic Interference Shielding ApplicationsPDF, Hydrothermal Synthesis and Characterization of Pure ZnO Nanoparticles for Energy Storage and Electromagnetic Interference Shielding ApplicationsOpen abstract

  In the present study, ZnO nanoparticles were synthesized using a hydrothermal method to investigate the influence of reaction duration on their structural, morphological, optical, dielectric, microwave, and electrochemical properties. ZnO nanoparticles were prepared at 2, 4, 6, 8, and 10 h under identical experimental conditions. X-ray diffraction analysis confirmed the formation of phase-pure hexagonal wurtzite ZnO, with crystallite size varying with hydrothermal duration. Among the investigated samples, the 8 h sample exhibited improved crystallinity and a uniform morphology. Optical studies confirmed the direct band-gap nature of ZnO, while photoluminescence and X-ray photoelectron spectroscopy revealed defect-related surface states. The dielectric response showed a clear dependence on frequency and reaction duration, with the 8 h sample exhibiting favourable dielectric characteristics. Microwave measurements demonstrated appreciable electromagnetic attenuation, with a minimum reflection loss of approximately −30 dB near 11 GHz. In addition, cyclic voltammetry and galvanostatic charge–discharge measurements were performed for the 8 h sample to assess its electrochemical behaviour. The obtained profiles confirmed measurable charge-storage capability under the investigated conditions. Overall, the results demonstrate that hydrothermal reaction duration is an important parameter for tailoring the multifunctional properties of ZnO nanoparticles. The 8 h sample shows promising potential for energy-storage and electromagnetic-interference shielding applications.

  https://doi.org/10.1149/2162-8777/aea7d7
• The following article is Open access
  Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiC

  Kang et al 

  View accepted manuscript, Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiCPDF, Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiCOpen abstract

  Low-voltage lateral trench split gate tri-gate MOSFETs (SGT-MOSFET) in 4H-SiC are proposed, fabricated, and investigated in this paper, comparing their performance with that of planar gate MOSFETs (PG-MOSFET). The tri-gate MOSFET features top channels on the (0001) face and additional sidewall channels on the (11-20) face, resulting in an increased effective channel width and higher electron mobility. The SGT-MOSFET exhibits drain currents 2.7 and 2.6 times higher than the PG-MOSFET at 25 °C and 200 °C, respectively. The gate oxide reliability is also examined preliminarily. These results highlight the potential of 4H-SiC tri-gate MOSFETs for low-voltage logic circuits and provide a basis for subsequent monolithic integration.

  https://doi.org/10.1149/2162-8777/ae9ce0
• Erratum—ZnO and Simonkolleite Nanocomposite Synthesis via Green Chemistry Using Hibiscus Flower Extract [ECS J. Solid State Sci. Technol., 10, 123016 (2021)]

  Aida 

  View accepted manuscript, Erratum—ZnO and Simonkolleite Nanocomposite Synthesis via Green Chemistry Using Hibiscus Flower Extract [ECS J. Solid State Sci. Technol., 10, 123016 (2021)]PDF, Erratum—ZnO and Simonkolleite Nanocomposite Synthesis via Green Chemistry Using Hibiscus Flower Extract [ECS J. Solid State Sci. Technol., 10, 123016 (2021)]Open abstract

  This paper was withdrawn by IOP Publishing on 3 June 2024. The funding information in the Acknowledgments was corrected as a post-publication change direct to the published article rather than as this erratum.

  https://doi.org/10.1149/2162-8777/ac6f21

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• The following article is Open access
  Plasma Etching of SiO₂ Using C=O-Containing Fluorocarbons with Low Global Warming Potentials

  Minuk Kim et al 2026 ECS J. Solid State Sci. Technol. 15 091001

  View article, Plasma Etching of SiO2 Using C=O-Containing Fluorocarbons with Low Global Warming PotentialsPDF, Plasma Etching of SiO2 Using C=O-Containing Fluorocarbons with Low Global Warming PotentialsOpen abstract

  SiO₂ was etched in plasmas of C=O-containing fluorocarbon compounds with global warming potentials (GWPs) of unity or lower, such as trifluoroacetyl fluoride (C₂F₄O), octafluoro-2-butanone (C₄F₈O), and heptafluoroisopropyl trifluoromethyl ketone (C₅F₁₀O), and their etch characteristics were compared with those of CHF₃, a hydrofluorocarbon with a high GWP of 14 600, in an inductively coupled plasma system. The etch rate was the lowest in the C₂F₄O/Ar plasma, whereas the etch rates in the C₄F₈O/Ar and C₅F₁₀O/Ar plasmas were comparable to that in the CHF₃/Ar plasma. X-ray photoelectron spectroscopy revealed that the steady-state fluorocarbon films formed on SiO₂ were thinner than 4 Å in all plasmas, indicating that the etch-rate trend was governed mainly by radical populations rather than film-thickness effects. Optical emission spectroscopy showed that the apparent total amount of CF₂, CF, and F radicals was lowest in C₂F₄O/Ar and similar in C₄F₈O/Ar, C₅F₁₀O/Ar, and CHF₃/Ar. The radical populations were rationalized by the bond dissociation energies and molecular structures of the discharge gases. These results demonstrate that C₄F₈O and C₅F₁₀O are promising environmentally sustainable alternatives to high-GWP CHF₃ for plasma etching of SiO₂.

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  Research Highlights

  • SiO₂ was etched in plasmas of C₂F₄O, C₄F₈O, and C₅F₁₀O with GWPs of unity or lower.

  • C₄F₈O/Ar and C₅F₁₀O/Ar plasmas etch SiO₂ as fast as high-GWP CHF₃/Ar plasma.

  • Etch rates were governed by CF₂, CF, and F radical populations measured by OES.

  • Bond dissociation energies and molecular structures explain radical generation.

  • GWP of the etch gas is reduced from 14 600 to below unity without tool changes.

  https://doi.org/10.1149/2162-8777/aea250
• The following article is Open access
  High-Efficiency Novel Cu₃InSnS₅ Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy Harvesting

  Oussama Taleb Jlidi et al 2026 ECS J. Solid State Sci. Technol. 15 095001

  View article, High-Efficiency Novel Cu3InSnS5 Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy HarvestingPDF, High-Efficiency Novel Cu3InSnS5 Quantum Dot Photovoltaics: From Quantum Confinement Modeling to Tandem Cell Optimization for Dual Indoor/Outdoor Energy HarvestingOpen abstract

  This study presents a comprehensive numerical optimization of single and tandem photovoltaic cells utilizing novel Cu₃InSnS₅ colloidal quantum dots (CQDs) as absorbers. These quaternary CQDs have emerged as a compelling class of low-dimensional materials due to their tunable optoelectronic properties and compliance with the Restriction of Hazardous Substances (RoHS) directive. A multi-scale simulation framework is employed, combining the envelope function approximation to predict size-dependent quantum confinement effects, Rigorous Coupled-Wave Analysis (RCWA) for optical modeling, and the Solar Cell Capacitance Simulator (SCAPS-1D) for device-level electrical optimization. By systematically tuning the CQD radius, buffer layer, and absorber thickness, the optimized single-junction cell achieves a power conversion efficiency of 11.53% under standard AM1.5G illumination, significantly surpassing the current experimental benchmark of <0.1%. Furthermore, a tandem architecture is designed to minimize thermalization losses, yielding an impressive efficiency of 31.97% under AM1.5G. Under indoor LED illumination (1250 lx), the single and tandem cells attain efficiencies of 12.13% and 22.21%, respectively. These findings underscore the immense potential of Cu₃InSnS₅ CQDs for dual indoor/outdoor energy harvesting, particularly for powering low-light Internet of Things (IoT) devices.

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  https://doi.org/10.1149/2162-8777/ae9db8
• The following article is Open access
  Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiC

  Kuan-Min Kang et al 2026 ECS J. Solid State Sci. Technol.

  View article, Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiCPDF, Demonstration of Low-Voltage Lateral Trench Split-Gate Tri-Gate MOSFETs in 4H-SiCOpen abstract

  Low-voltage lateral trench split gate tri-gate MOSFETs (SGT-MOSFET) in 4H-SiC are proposed, fabricated, and investigated in this paper, comparing their performance with that of planar gate MOSFETs (PG-MOSFET). The tri-gate MOSFET features top channels on the (0001) face and additional sidewall channels on the (11-20) face, resulting in an increased effective channel width and higher electron mobility. The SGT-MOSFET exhibits drain currents 2.7 and 2.6 times higher than the PG-MOSFET at 25 °C and 200 °C, respectively. The gate oxide reliability is also examined preliminarily. These results highlight the potential of 4H-SiC tri-gate MOSFETs for low-voltage logic circuits and provide a basis for subsequent monolithic integration.

  https://doi.org/10.1149/2162-8777/ae9ce0
• The following article is Open access
  Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction Devices

  Hsiao-Hsuan Wan et al 2026 ECS J. Solid State Sci. Technol. 15 085002

  View article, Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction DevicesPDF, Effects of Gamma Irradiation on Electrical Characteristics and Carrier Dynamics in Diamond Schottky and Heterojunction DevicesOpen abstract

  Diamond-based devices are promising for operation in radiation environments due to their wide bandgap and strong atomic bonding. In this work, the effects of Co-60 gamma irradiation to a total dose of 1 Mrad on the electrical characteristics and carrier dynamics of diamond Schottky and indium-tin oxide (ITO)/boron doped diamond heterojunction rectifiers are investigated. The rectifiers were exposed to gamma radiation with photon energies of 1.17 and 1.33 MeV, where ionization dominates over displacement damage. The Schottky diodes exhibit minimal changes in both forward and reverse current characteristics after irradiation, indicating stable metal/diamond interfaces. In contrast, the heterojunction devices show a positive shift of forward IV around the diode turn-on voltage and an increased ideality factor, suggesting modification of charge accumulation in the ITO. The changes in electrical characteristics for both rectifiers are reversible by application of short forward current pulses during repeated measurement of the current–voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers under the irradiation conditions used in this study. Reverse current shows only minor variation for both types of rectifiers, confirming the absence of significant bulk leakage paths. Reverse recovery measurements reveal a reduction in recovery time after irradiation, attributed to decreased carrier lifetime and reduced stored charge due to radiation-induced traps. The extracted carrier concentration from the capacitance–voltage analysis changes only slightly from 1.23 × 10¹⁶ to 1.20 × 10¹⁶ cm⁻³ after irradiation confirming that gamma irradiation does not induce measurable degradation in bulk electrical properties under the irradiation conditions used in this study. While isolated Frenkel defects or other point defects may be generated during gamma irradiation, their concentration is evidently too low to produce measurable changes in carrier concentration or leakage current. The corresponding carrier removal rate is on the order of ∼0.1 cm⁻¹. This small variation indicates that gamma irradiation does not significantly affect the bulk carrier concentration in diamond. These results indicate that gamma irradiation primarily affects carrier dynamics and interface properties, while the bulk diamond remains largely unaffected. Thus, diamond-based rectifiers may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.

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  https://doi.org/10.1149/2162-8777/ae9593
• The following article is Open access
  Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS Applications

  Vincent Pares et al 2026 ECS J. Solid State Sci. Technol. 15 084003

  View article, Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS ApplicationsPDF, Chemical Mechanical Polishing of In-Situ-Doped Polysilicon for MEMS ApplicationsOpen abstract

  The present work presents a 200 mm wafer-scale single step industrial Chemical Mechanical Polishing (CMP) process to polish in situ doped polysilicon using a commercial silica-based slurry. By tuning CMP operating conditions and pad conditioning, the surface roughness is reduced uniformly across the wafer down to Rq = 0.22 nm. The observed trends suggest that, within the investigated process window, slurry chemistry plays a role in achieving the lowest roughness, while pad conditioning strongly influences polishing uniformity. In particular, gentler conditioning parameters and less aggressive disk lowers nanoscale surface roughness and improves wafer-scale uniformity. A minimum material removal is required to reach the lowest roughness. Beyond this threshold, Rq remains stable and independent of additional removal. The same behavior is observed over four different ISDP film materials, regardless of the film thickness or post-deposition annealing. Hydrophobic direct bonding of a polished ISDP wafer to a monocrystalline silicon one, yielded defect free interface and high bond strength, demonstrating the potential of the ISDP CMP process to produce surfaces compatible with demanding wafer level packaging requirements.

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  Highlights

  • Achieved 0.22 nm RMS roughness uniformly on four in situ doped polysilicon films (thickness, anneal)

  • Single step CMP on 200 mm production tool using commercial silica slurry

  • Gentler pad conditioning improved nanoscale roughness and wafer scale uniformity

  • Only a few nanometers removal needed; beyond a threshold, roughness stayed stable

  • Final surface roughness meets hydrophobic direct bonding needs for MEMS wafer packaging

  https://doi.org/10.1149/2162-8777/ae72cd
• The following article is Open access
  Electron Beam Irradiation-Induced Transport and Recombination in P-type Diamond Diodes

  Gabriel P Marciaga et al 2026 ECS J. Solid State Sci. Technol. 15 075004

  View article, Electron Beam Irradiation-Induced Transport and Recombination in P-type Diamond DiodesPDF, Electron Beam Irradiation-Induced Transport and Recombination in P-type Diamond DiodesOpen abstract

  This study investigates minority carrier diffusion length (L) and defect-mediated recombination phenomena in boron-doped p-type diamond epitaxial layers. Utilizing temperature-dependent electron beam-induced current (EBIC) and cathodoluminescence (CL), the influence of temperature and sustained electron beam irradiation was characterized. The diamond sample demonstrates a pronounced thermal enhancement to the minority carrier diffusion length. This temperature enhancement for L has an activation energy of 177 meV. Furthermore, sustained electron injection induces a near-linear elongation of the diffusion length through passivation of deep-level defects. From the EBIC injection data, an activation energy of 151 meV was extracted from fitting. Temperature-resolved CL reveals the quenching of the characteristic A-band emission at 100 °C. Additionally, a thermal activation energy of 112 meV was extracted via a decay fit of the temperature dependent CL intensity data. While sustained electron beam irradiation reveals dose-dependent quenching of the A-band emission with thermally activated decay rates. This yields activation energies of 110 meV and 11 meV associated with distinct defect generation mechanisms at high and low temperatures, respectively. This provides a complementary assessment of the defect landscape governing minority carrier lifetimes in these boron-doped diamond diodes.

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  https://doi.org/10.1149/2162-8777/ae87cd
• The following article is Open access
  Impact of Channel Width on Electrical Characteristics for Inversion Mode N-Channel TFT on Polycrystalline Ge by Solid Phase Crystallization

  Linyu Huang et al 2026 ECS J. Solid State Sci. Technol. 15 064006

  View article, Impact of Channel Width on Electrical Characteristics for Inversion Mode N-Channel TFT on Polycrystalline Ge by Solid Phase CrystallizationPDF, Impact of Channel Width on Electrical Characteristics for Inversion Mode N-Channel TFT on Polycrystalline Ge by Solid Phase CrystallizationOpen abstract

  We have successfully synthesized high-quality polycrystalline (poly-) Ge thin films using an advanced solid-phase crystallization (SPC) technique and fabricated inversion-mode n-channel thin-film transistors (TFTs) on a glass substrate. However, its electrical performance still had room for improvement. Although the effect of channel geometry on device performance in poly-Si TFTs has been widely studied, similar consideration for poly-Ge TFTs has not been reported. In this study, we examined the effect of channel width on TFT performance metrics, including subthreshold swing, ON/OFF ratio, and threshold voltage. By changing the channel shape by reducing the channel width, the ON/OFF ratio of n-channel poly-Ge TFTs was significantly improved, and the behavior of other electrical properties is similar to that of poly-Si TFTs. Additionally, by changing the channel width of poly-Ge TFT, we determined the mobility of the grain boundaries in parallel to current flow within poly-Ge. The trend of estimated grain boundary’s mobility relative to the whole poly-Ge film mobility is similar to that of poly-Si, as estimated from complex simulation. This method can evaluate the conductive properties of grain boundaries in polycrystalline semiconductors and can be applied to polycrystalline semiconductors prepared using various methods.

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  https://doi.org/10.1149/2162-8777/ae79a7
• The following article is Open access
  Characteristics of β-Ga₂O₃/Al₂O₃/Pt Capacitors with a Ga₂O₃ Surface Modified Using the Dummy-SiO₂ Process

  Toshihide Nabatame et al 2026 ECS J. Solid State Sci. Technol. 15 064005

  View article, Characteristics of β-Ga2O3/Al2O3/Pt Capacitors with a Ga2O3 Surface Modified Using the Dummy-SiO2 ProcessPDF, Characteristics of β-Ga2O3/Al2O3/Pt Capacitors with a Ga2O3 Surface Modified Using the Dummy-SiO2 ProcessOpen abstract

  The characteristics of β-Ga₂O₃/Al₂O₃/Pt capacitors fabricated via the dummy-SiO₂ (d-SiO₂) process at 800 °C under O₂ (D-O₂), N₂ (D-N₂), and 3% H₂ (D-H₂) atmospheres were investigated. The surface of Ga₂O₃ after the d-SiO₂ process was as smooth as that after the sulfuric acid-hydrogen peroxide mixture treatment (Control). The flatband voltage (V_fb) hysteresis decreased as follows: Control (0.76 V) > D-H₂ (0.56 V) > D-N₂ (0.43 V) > D-O₂ (0.37 V). The interface state density of the D-O₂ capacitor was significantly reduced to 6 × 10¹¹ cm⁻²eV⁻¹ at −0.4 eV from conduction band. The V_fb shift caused by the electron traps according to the near-interface trap model under positive bias stress substantially improved for the capacitors fabricated by the d-SiO₂ process. The poor characteristics of the Control capacitor are due to the presence of the unstable layer on the Ga₂O₃ surface. The improved electrical characteristic of the d-SiO₂ capacitors is due to the modified Ga₂O₃ surface, which eliminated the unstable Ga₂O₃ layer. This is the result of hydrogen contained within the dummy SiO₂ layer supporting the removal of Ga₂O₃. The difference in the decomposition reaction of Ga₂O₃ due to the atmosphere gas of the d-SiO₂ process leads to differences in electrical properties.

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  https://doi.org/10.1149/2162-8777/ae7ac0
• The following article is Open access
  Investigation of Electrochemical Transport, Gate Leakage, and Transconductance Behavior in PEDOT:PSS Organic Electrochemical Transistors

  Vinay Budhraja et al 2026 ECS J. Solid State Sci. Technol. 15 067001

  View article, Investigation of Electrochemical Transport, Gate Leakage, and Transconductance Behavior in PEDOT:PSS Organic Electrochemical TransistorsPDF, Investigation of Electrochemical Transport, Gate Leakage, and Transconductance Behavior in PEDOT:PSS Organic Electrochemical TransistorsOpen abstract

  Organic Electrochemical Transistors (OECTs) are promising candidates for low-voltage bioelectronic systems due to their high transconductance, mixed ionic–electronic transport, and compatibility with flexible substrates. In this work, we investigate the electrochemical transport, gate leakage, and transconductance behavior of screen-printed PEDOT:PSS OECTs, with emphasis on the relationship between ionic coupling and output characteristics. Key electrical and electrochemical parameters—including drain current modulation, transconductance evolution, gate current behavior, and capacitance–voltage response—were systematically analyzed to elucidate the mechanisms governing device operation. The results reveal clear trade-offs between parasitic resistance, volumetric electrochemical capacitance, and effective gate control, which in turn influence signal integrity and amplification efficiency. Devices exhibiting reduced parasitic effects demonstrated lower gate leakage, improved signal-to-noise ratio, and more stable transconductance, whereas devices with stronger ionic coupling showed enhanced drain current at the expense of nonlinearity in the saturation regime. High-frequency C–V measurements and gate-current modeling further confirm distinct electrochemical dynamics driven by modulation of mixed conduction pathways. These insights provide a deeper understanding of OECT operation and offer practical guidelines for optimizing device architecture in solid-state and flexible bioelectronic applications.

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  https://doi.org/10.1149/2162-8777/ae7642
• The following article is Open access
  Impact of Face-to-Face Annealing on the Structural and Optical Stability of Sputtered Al_0.70Sc_0.30N Thin Films

  Sihang Hui et al 2026 ECS J. Solid State Sci. Technol. 15 064002

  View article, Impact of Face-to-Face Annealing on the Structural and Optical Stability of Sputtered Al0.70Sc0.30N Thin FilmsPDF, Impact of Face-to-Face Annealing on the Structural and Optical Stability of Sputtered Al0.70Sc0.30N Thin FilmsOpen abstract

  Reactive sputter deposition of Al_1−xSc_xN has shown great promise in the fabrication of next generation piezoelectric, ferroelectric, and optoelectronic applications. Due to the nature of sputtering, post-deposition, high temperature thermal processing is often used to improve the film crystalline quality and subsequently improve the overall device performance. However, a complete analysis on the thermal stability of high Sc content Al_1−xSc_xN remains as a gap that needs to be filled. In this work, reactive sputtered Al_0.70Sc_0.30N was annealed using a face-to-face configuration at temperatures between 1100 °C and 1300 °C, and for durations between 60 and 180 min to study the thermal impact on structural and optical properties. Annealing at 1100 °C for 60 mins under this configuration improved the thin film crystalline quality while maintaining phase purity and structural stability. Annealing at higher temperatures and durations led to ScN segregation, as well as Sc₂O₃ formation at the highest temperature regime. Optically, it was found that annealing can eliminate vacancy-oxygen complex defects and improve transmission in the deposited thin film.

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  https://doi.org/10.1149/2162-8777/ae6a6b

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• The following article is Open access
  Review—Ionizing Radiation Damage Effects on GaN Devices

  S. J. Pearton et al 2016 ECS J. Solid State Sci. Technol. 5 Q35

  View article, Review—Ionizing Radiation Damage Effects on GaN DevicesPDF, Review—Ionizing Radiation Damage Effects on GaN DevicesOpen abstract

  Gallium Nitride based high electron mobility transistors (HEMTs) are attractive for use in high power and high frequency applications, with higher breakdown voltages and two dimensional electron gas (2DEG) density compared to their GaAs counterparts. Specific applications for nitride HEMTs include air, land and satellite based communications and phased array radar. Highly efficient GaN-based blue light emitting diodes (LEDs) employ AlGaN and InGaN alloys with different compositions integrated into heterojunctions and quantum wells. The realization of these blue LEDs has led to white light sources, in which a blue LED is used to excite a phosphor material; light is then emitted in the yellow spectral range, which, combined with the blue light, appears as white. Alternatively, multiple LEDs of red, green and blue can be used together. Both of these technologies are used in high-efficiency white electroluminescent light sources. These light sources are efficient and long-lived and are therefore replacing incandescent and fluorescent lamps for general lighting purposes. Since lighting represents 20–30% of electrical energy consumption, and because GaN white light LEDs require ten times less energy than ordinary light bulbs, the use of efficient blue LEDs leads to significant energy savings. GaN-based devices are more radiation hard than their Si and GaAs counterparts due to the high bond strength in III-nitride materials. The response of GaN to radiation damage is a function of radiation type, dose and energy, as well as the carrier density, impurity content and dislocation density in the GaN. The latter can act as sinks for created defects and parameters such as the carrier removal rate due to trapping of carriers into radiation-induced defects depends on the crystal growth method used to grow the GaN layers. The growth method has a clear effect on radiation response beyond the carrier type and radiation source. We review data on the radiation resistance of AlGaN/GaN and InAlN/GaN HEMTs and GaN–based LEDs to different types of ionizing radiation, and discuss ion stopping mechanisms. The primary energy levels introduced by different forms of radiation, carrier removal rates and role of existing defects in GaN are discussed. The carrier removal rates are a function of initial carrier concentration and dose but not of dose rate or hydrogen concentration in the nitride material grown by Metal Organic Chemical Vapor Deposition. Proton and electron irradiation damage in HEMTs creates positive threshold voltage shifts due to a decrease in the two dimensional electron gas concentration resulting from electron trapping at defect sites, as well as a decrease in carrier mobility and degradation of drain current and transconductance. State-of-art simulators now provide accurate predictions for the observed changes in radiation-damaged HEMT performance. Neutron irradiation creates more extended damage regions and at high doses leads to Fermi level pinning while ⁶⁰Co γ-ray irradiation leads to much smaller changes in HEMT drain current relative to the other forms of radiation. In InGaN/GaN blue LEDs irradiated with protons at fluences near 10¹⁴ cm⁻² or electrons at fluences near 10¹⁶ cm⁻², both current-voltage and light output-current characteristics are degraded with increasing proton dose. The optical performance of the LEDs is more sensitive to the proton or electron irradiation than that of the corresponding electrical performances.

  https://doi.org/10.1149/2.0251602jss
• The following article is Open access
  Review—Photoluminescence Properties of Cr³⁺-Activated Oxide Phosphors

  Sadao Adachi 2021 ECS J. Solid State Sci. Technol. 10 026001

  View article, Review—Photoluminescence Properties of Cr3+-Activated Oxide PhosphorsPDF, Review—Photoluminescence Properties of Cr3+-Activated Oxide PhosphorsOpen abstract

  The Cr³⁺-activated phosphor properties are discussed in detail from an aspect of spectroscopic point of view. The host materials considered here are a various kind of oxide compounds. The photoluminescence (PL) and PL excitation spectra of the Cr³⁺-activated oxide phosphors are analyzed based on Franck−Condon analysis within the configurational-coordinate model. A new method is proposed for obtaining reliable crystal-field (Dq) and Racah parameters (B and C) based on a general ligand field theory with paying an attention to difficulty in the exact estimation of such important ligand field parameters. The intra-d-shell Cr³⁺ states, such as ²E_g (²G), ⁴T_2g (⁴F), and ⁴T_1g (⁴F), in various oxide hosts are determined and plotted against Dq in the Tanabe−Sugano energy-level diagram. The results obtained are summarized in graphical and tabular forms. A comparative discussion of Cr³⁺ ion as an efficient activator in oxide and fluoride hosts is also given. The present analysis method can be used to predict an energy of Cr³⁺ emission and/or to check a validity of the Racah parameter values for a variety of Cr³⁺-activated phosphors and related optical and optoelectronic device applications.

  https://doi.org/10.1149/2162-8777/abdc01
• The following article is Open access
  Review—Influence of Processing Parameters to Control Morphology and Optical Properties of Sol-Gel Synthesized ZnO Nanoparticles

  Sandeep Arya et al 2021 ECS J. Solid State Sci. Technol. 10 023002

  View article, Review—Influence of Processing Parameters to Control Morphology and Optical Properties of Sol-Gel Synthesized ZnO NanoparticlesPDF, Review—Influence of Processing Parameters to Control Morphology and Optical Properties of Sol-Gel Synthesized ZnO NanoparticlesOpen abstract

  ZnO has several potential applications into its credit. This review article focuses on the influence of processing parameters involved during the synthesis of ZnO nanoparticles by sol-gel method. During the sol-gel synthesis technique, the processing parameters/experimental conditions can affect the properties of the synthesized material. Processing parameters are the operating conditions that are to be kept under consideration during the synthesis process of nanoparticles so that various properties exhibited by the resulting nanoparticles can be tailored according to the desired applications. Effect of parameters like pH of the sol, additives used (like capping agent, surfactant), the effect of annealing temperature and calcination on the morphology and the optical properties of ZnO nanoparticles prepared via sol-gel technique is analyzed in this study. In this study, we tried to brief the experimental investigations done by various researchers to analyze the influence of processing parameters on ZnO nanoparticles. This study will provide a platform to understand and establish a correlation between the experimental conditions and properties of ZnO nanoparticles prepared through sol-gel route which will be helpful in meeting the desired needs in various application areas.

  https://doi.org/10.1149/2162-8777/abe095
• The following article is Open access
  Perspective—Opportunities and Future Directions for Ga₂O₃

  Michael A. Mastro et al 2017 ECS J. Solid State Sci. Technol. 6 P356

  View article, Perspective—Opportunities and Future Directions for Ga2O3PDF, Perspective—Opportunities and Future Directions for Ga2O3Open abstract

  The β-polytype of Ga₂O₃ has a bandgap of ∼4.8 eV, can be grown in bulk form from melt sources, has a high breakdown field of ∼8 MV.cm⁻¹ and is promising for power electronics and solar blind UV detectors, as well as extreme environment electronics (high temperature, high radiation, and high voltage (low power) switching. High quality bulk Ga₂O₃ is now commercially available from several sources and n-type epi structures are also coming onto the market. There are also significant efforts worldwide to grow more complex epi structures, including β-(Al_xGa_1x)₂O₃/Ga₂O₃ and β-(In_xGa_1−x)₂O₃/Ga₂O₃ heterostructures, and thus this materials system is poised to make rapid advances in devices. To fully exploit these advantages, advances in bulk and epitaxial crystal growth, device design and processing are needed. This article provides some perspectives on these needs.

  https://doi.org/10.1149/2.0031707jss
• The following article is Open access
  Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and Applications

  Alain E. Kaloyeros et al 2020 ECS J. Solid State Sci. Technol. 9 063006

  View article, Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and ApplicationsPDF, Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: State-of-the-Art Processing Technologies, Properties, and ApplicationsOpen abstract

  Accelerating interest in silicon nitride thin film material system continues in both academic and industrial communities due to its highly desirable physical, chemical, and electrical properties and the potential to enable new device technologies. As considered here, the silicon nitride material system encompasses both non-hydrogenated (SiN_x) and hydrogenated (SiN_x:H) silicon nitride, as well as silicon nitride-rich films, defined as SiN_x with C inclusion, in both non-hydrogenated (SiN_x(C)) and hydrogenated (SiN_x:H(C)) forms. Due to the extremely high level of interest in these materials, this article is intended as a follow-up to the authors’ earlier publication [A. E. Kaloyeros, F. A. Jové, J. Goff, B. Arkles, Silicon nitride and silicon nitride-rich thin film technologies: trends in deposition techniques and related applications, ECS J. Solid State Sci. Technol., 6, 691 (2017)] that summarized silicon nitride research and development (R&D) trends through the end of 2016. In this survey, emphasis is placed on cutting-edge achievements and innovations from 2017 through 2019 in Si and N source chemistries, vapor phase growth processes, film properties, and emerging applications, particularly in heterodevice areas including sensors, biointerfaces and photonics.

  https://doi.org/10.1149/2162-8777/aba447
• The following article is Open access
  Atomic Layer Etching at the Tipping Point: An Overview

  G. S. Oehrlein et al 2015 ECS J. Solid State Sci. Technol. 4 N5041

  View article, Atomic Layer Etching at the Tipping Point: An OverviewPDF, Atomic Layer Etching at the Tipping Point: An OverviewOpen abstract

  The ability to achieve near-atomic precision in etching different materials when transferring lithographically defined templates is a requirement of increasing importance for nanoscale structure fabrication in the semiconductor and related industries. The use of ultra-thin gate dielectrics, ultra thin channels, and sub-20 nm film thicknesses in field effect transistors and other devices requires near-atomic scale etching control and selectivity. There is an emerging consensus that as critical dimensions approach the sub-10 nm scale, the need for an etching method corresponding to Atomic Layer Deposition (ALD), i.e. Atomic Layer Etching (ALE), has become essential, and that the more than 30-year quest to complement/replace continuous directional plasma etching (PE) methods for critical applications by a sequence of individual, self-limited surface reaction steps has reached a crucial stage. A key advantage of this approach relative to continuous PE is that it enables optimization of the individual steps with regard to reactant adsorption, self-limited etching, selectivity relative to other materials, and damage of critical surface layers. In this overview we present basic approaches to ALE of materials, discuss similarities/crucial differences relative to thermal and plasma-enhanced ALD, and then review selected results on ALE of materials aimed at pattern transfer. The overview concludes with a discussion of opportunities and challenges ahead.

  https://doi.org/10.1149/2.0061506jss
• Review—Radiation Damage in Wide and Ultra-Wide Bandgap Semiconductors

  S. J. Pearton et al 2021 ECS J. Solid State Sci. Technol. 10 055008

  View article, Review—Radiation Damage in Wide and Ultra-Wide Bandgap SemiconductorsPDF, Review—Radiation Damage in Wide and Ultra-Wide Bandgap SemiconductorsOpen abstract

  The wide bandgap semiconductors SiC and GaN are already commercialized as power devices that are used in the automotive, wireless, and industrial power markets, but their adoption into space and avionic applications is hindered by their susceptibility to permanent degradation and catastrophic failure from heavy-ion exposure. Efforts to space-qualify these wide bandgap power devices have revealed that they are susceptible to damage from the high-energy, heavy-ion space radiation environment (galactic cosmic rays) that cannot be shielded. In space-simulated conditions, GaN and SiC transistors have shown failure susceptibility at ∼50% of their nominal rated voltage. Similarly, SiC transistors are susceptible to radiation damage-induced degradation or failure under heavy-ion single-event effects testing conditions, reducing their utility in the space galactic cosmic ray environment. In SiC-based Schottky diodes, catastrophic single-event burnout (SEB) and other single-event effects (SEE) have been observed at ∼40% of the rated operating voltage, as well as an unacceptable degradation in leakage current at ∼20% of the rated operating voltage. The ultra-wide bandgap semiconductors Ga₂O₃, diamond and BN are also being explored for their higher power and higher operating temperature capabilities in power electronics and for solar-blind UV detectors. Ga₂O₃ appears to be more resistant to displacement damage than GaN and SiC, as expected from a consideration of their average bond strengths. Diamond, a highly radiation-resistant material, is considered a nearly ideal material for radiation detection, particularly in high-energy physics applications. The response of diamond to radiation exposure depends strongly on the nature of the growth (natural vs chemical vapor deposition), but overall, diamond is radiation hard up to several MGy of photons and electrons, up to 10¹⁵ (neutrons and high energetic protons) cm⁻² and >10¹⁵ pions cm⁻². BN is also radiation-hard to high proton and neutron doses, but h-BN undergoes a transition from sp² to sp³ hybridization as a consequence of the neutron induced damage with formation of c-BN. Much more basic research is needed on the response of both the wide and ultra-wide bandgap semiconductors to radiation, especially single event effects.

  https://doi.org/10.1149/2162-8777/abfc23
• The following article is Open access
  Investigation of InAlN Layers Surface Reactivity after Thermal Annealings: A Complete XPS Study for HEMT

  Y. Bourlier et al 2018 ECS J. Solid State Sci. Technol. 7 P329

  View article, Investigation of InAlN Layers Surface Reactivity after Thermal Annealings: A Complete XPS Study for HEMTPDF, Investigation of InAlN Layers Surface Reactivity after Thermal Annealings: A Complete XPS Study for HEMTOpen abstract

  The surface chemistry of InAlN ultra-thin layers, having undergone an oxidation procedure usually running through the HEMT fabrication process (850°C, O₂ and O₂+Ar) is studied by XPS. The suitability of XPS analysis to operate as a retro-engineering tool for added value microelectronic devices fabrication is shown. A precise examination of the Al2p, In3d_5/2, N1s, and O1s peaks directly informs about spatial and atomic arrangement. The formation of a covering 3 nm surface oxide is evidenced after O₂ annealing. Once annealed, two specific additional N1s contributions are shown, at higher (404.0 eV) and lower binding energies (397.4 eV) compared to the InAlN matrix one (396.5 eV). To our knowledge, such fingerprint is rather unusual for ternary III-V materials. It reveals the formation of a nitrogen deficient interlayer, situated between the oxide overlayer and the undisturbed matrix, and the presence of interstitial N₂ molecules trapped at the interface. After Ar annealing, both oxide and interface layers are partially reorganized. InAlN reactivity toward higher annealing temperature (950°C) and its stability over time is finally discussed. N₂ molecules are unstable and progressively eliminated in time although nitrogen deficient interlayer still remains. Thermal treatments below 850°C are recommended to preserve the barrier chemical integrity.

  https://doi.org/10.1149/2.0181806jss
• Study of Optical, Thermal, Electrical, and Impedance Properties of Li₄Ti₅O₁₂-Based PEO/SA Biopolymer Blend Electrolytes for Lithium-Ion Batteries

  F. E. Hanash et al 2025 ECS J. Solid State Sci. Technol. 14 023011

  View article, Study of Optical, Thermal, Electrical, and Impedance Properties of Li4Ti5O12-Based PEO/SA Biopolymer Blend Electrolytes for Lithium-Ion BatteriesPDF, Study of Optical, Thermal, Electrical, and Impedance Properties of Li4Ti5O12-Based PEO/SA Biopolymer Blend Electrolytes for Lithium-Ion BatteriesOpen abstract

  Nanocomposites composed of polyethylene oxide (PEO) and sodium alginate (SA), containing varying contents of lithium titanium oxide nanoparticles (Li₄Ti₅O₁₂NPs), were synthesized by solution casting technique. Li₄Ti₅O₁₂ was incorporated into PEO/SA blend and is a valuable biopolymer for its biocompatibility, solubility and eco-friendliness. Structural analysis via X-ray diffraction spectroscopy revealed a decrease in the crystallinity of PEO/SA matrix with increasing nanoparticle content. Complementary Fourier transform infrared analysis verified the presence of strong molecular interactions between Li₄Ti₅O₁₂ and the blend chains. Scanning electron microscopy verified a uniform dispersion of Li₄Ti₅O₁₂ within PEO/SA blend, contributing to the improved properties of the electrolytes, while optical analysis showed a decrease in the bandgap energy, indicating enhanced light absorption and improved suitability for applications in nanodielectric devices. The thermal stability of PEO/SA/Li₄Ti₅O₁₂ electrolyte samples was improved as shown by thermogravimetric analysis. Furthermore, a significant improvement in the ionic conductivity of the filled samples was observed, attributed to the reduced bulk resistance and improved charge transport pathways. Dielectric studies further showed improved dielectric permittivity and reduced dielectric losses for filled samples, enhancing the material’s charge storage capability. These findings highlight the potential of PEO/SA/Li₄Ti₅O₁₂ biopolymer electrolytes for advanced applications in nanodielectric devices and lithium-ions batteries.

  https://doi.org/10.1149/2162-8777/adb78e
• The following article is Open access
  Review—Mn⁴⁺-Activated Red and Deep Red-Emitting Phosphors

  Sadao Adachi 2020 ECS J. Solid State Sci. Technol. 9 016001

  View article, Review—Mn4+-Activated Red and Deep Red-Emitting PhosphorsPDF, Review—Mn4+-Activated Red and Deep Red-Emitting PhosphorsOpen abstract

  Mn⁴⁺-activated phosphors are a new class of non-rare earth phosphors and are alternative to commercial Eu²⁺-activated nitride/oxynitride phosphors with growing interest in various applications. In this review article, the structural and photoluminescence (PL) properties of various Mn⁴⁺-activated phosphors have been discussed. The host materials considered here can be roughly classified into five groups; fluorides, oxides, oxyfluorides, and two fluorine compounds. Phosphors of each group can also be classified into totally eleven subgroups from their different PL spectral features, e.g., whether an appearance of the zero-phonon line (ZPL) emission peak or not. The ZPL emission and absorption energies of the Mn⁴⁺ ions have been determined from the PL and PL excitation spectra using the Franck−Condon analysis method within the configurational-coordinate (CC) model. These results are used to obtain reliable phosphor parameters, i.e., the crystal-field (Dq) and Racah parameters (B and C), of the Mn⁴⁺ ions in the various host materials. The PL intensity vs temperature data, together with those of the luminescence lifetimes, are modeled on the basis of the CC model, and an excellent agreement has been achieved if not only the optical phonon but also the acoustic phonon contribution is taken into consideration in the conventional thermal quenching model. Effects of the hydrostatic pressure and dopant concentration on the PL spectral features are also discussed. Finally, key properties of the Mn⁴⁺-activated phosphors are discussed for use of such red and deep red-emitting phosphor systems in warm w-LED and indoor plant cultivation applications.

  https://doi.org/10.1149/2.0022001JSS