Article
Chemistry, Multidisciplinary
Liuhui Lei, Yuanyuan Tan, Xing Yuan, Wei Dou, Jiale Zhang, Yongkang Wang, Sizhe Zeng, Shenyi Deng, Haoting Guo, Weichang Zhou, Dongsheng Tang
Summary: A flexible electric-double-layer thin film transistor (TFT) based on a vertical InGaZnO4 channel was fabricated at room temperature, exhibiting low operation voltage, high current on/off ratio, and good subthreshold swing. The new transistor shows great potential for low-power portable flexible electronics applications.
Article
Chemistry, Physical
Dohwan Jung, Yoonseo Jang, Prakash R. Sultane, Christopher W. Bielawski, Jungwoo Oh
Summary: The energy-band alignment between atomic layer-deposited beryllium oxide (BeO) films and beta-Ga2O3 substrates is reported. It was found that the ALD BeO dielectric on the beta-Ga2O3 substrate provides a higher conduction band offset, which has the potential to lower the gate leakage current density of beta-Ga2O3 power devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Multidisciplinary
Lin Tao, Bin Yao, Qian Yue, Zhiying Dan, Peiting Wen, Mengmeng Yang, Zhaoqiang Zheng, Dongxiang Luo, Weijun Fan, Xiaozhou Wang, Wei Gao
Summary: Our work presents a new universal method for fabricating a topological insulator and paves the way for the construction of novel van der Waals tunneling structures.
Article
Materials Science, Multidisciplinary
Neelima Singh, Alpana Agarwal, Mohit Agarwal
Summary: The study investigates the effect of band offsets engineering for lead-free all-inorganic double-perovskite solar cell and finds that within a certain range, the conduction band offset and valence band offset can improve device performance. The optimal combination of electron transport layer and hole transport layer is proposed to further enhance the overall power conversion efficiency of the cell.
Article
Chemistry, Inorganic & Nuclear
Zohra Nazir Kayani, Ammara Iqbal, Zainab Bashir, Saira Riaz, Shahzad Naseem
Summary: Researchers are increasingly interested in thin film materials due to the growing demand in the electronics industry. In this study, K-doped TiO2 thin films were synthesized using sol-gel dip-coating, and the effects of K concentration on the properties of the films were investigated. The results showed that K doping had a significant impact on the morphological, structural, magnetic, dielectric, antibacterial, and optical characteristics of the TiO2 films.
INORGANIC CHEMISTRY COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Neeraj Goel, Rahul Kumar, Mahesh Kumar
Summary: The research investigates the band alignment at the MoS2/Ge heterojunction and identifies a type-II band alignment, which allows for efficient carrier recombination through spatial confinement. The calculation of band offset parameters offers a promising new approach for device engineering across the MoS2/Ge heterojunction interface.
Article
Chemistry, Multidisciplinary
Jose C. Conesa
Summary: This study compares two DFT methods for predicting band offsets at semiconductor interfaces, one using individual slabs and vacuum and the other using alternating slabs with hybrid functionals. The research suggests that the alternating slabs method is the preferred choice when epitaxial mismatch is not a significant issue.
Article
Energy & Fuels
Junyi Feng, Guanzhao Wen, Rong Hu, Jun Peng, Hong Lu, Ningjiu Zhao, Xianshao Zou, Wei Zhang
Summary: Recent research has shown that low-energy offset polymer solar cells (PSCs) can achieve a power conversion efficiency of over 19%. The study investigates the correlation between energy offsets and the charge photogeneration process in Y-series molecule-based PSCs. The findings reveal the importance of energy offsets for efficient charge photogeneration and recombination in ultrafast timescales for high-performance PSCs.
Article
Physics, Multidisciplinary
Neetika Yadav, Ayush Khare
Summary: An extensive study has been conducted on the non-radiative recombination losses in absorber double perovskite material. Four device configurations with different electron transport layers have been proposed and examined thoroughly for their photovoltaic parameters. The simulation results show that the WS2-based device with the FTO/WS2/LNMO/Cu2O/Au configuration exhibits the highest power conversion efficiency of 24.08% after optimization. This work demonstrates the potential of the eco-friendly and non-toxic material La2NiMnO6 for high-efficiency perovskite devices.
Article
Optics
Najla M. Khusayfan, A. F. Qasrawi, Seham R. Alharbi, Hazem K. Khanfar, T. S. Kayed
Summary: The study explores the properties of CdSe/GeO2 heterojunctions, finding that stacking GeO2 onto CdSe enhances crystallinity, modifies the energy band gap, and increases carrier drift mobility. The coating is also shown to be suitable for optoelectronic device applications. Illumination intensity dependent photosensitivity and MOSFET characteristics were observed in the device.
Review
Chemistry, Multidisciplinary
Hang Luo, Fan Wang, Ru Guo, Dou Zhang, Guanghu He, Sheng Chen, Qing Wang
Summary: This article summarizes the latest research on all-organic polymer dielectrics, including molecular structure design, polymer blends, and layered structured polymers. The challenges in the field and suggestions for future research on high-energy-density polymer dielectrics are also presented.
Article
Engineering, Electrical & Electronic
Konstantina Iordanidou, Clas Persson
Summary: In this study, the fundamental properties of crystalline InGaZnO4 were analyzed, identifying the most stable Ga/Zn atomic distribution patterns and revealing its characteristics as an indirect band-gap semiconductor. The material exhibits good electron mobility and suppressed hole mobility, resulting in lower power consumption in future InGaZnO4-based transistors.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Engineering, Electrical & Electronic
Hendrik F. W. Dekkers, Michiel J. van Setten, Attilio Belmonte, Adrian Chasin, Subhali Subhechha, Nouredine Rassoul, Anastasia Glushkova, Romain Delhougne, Gouri Sankar Kar
Summary: Polycrystalline indium-gallium-zinc oxide (IGZO) in the spinel phase was successfully obtained by physical vapor deposition (PVD) and its growth process and electrical properties were investigated. It was found that spinel IGZO exhibited higher channel field-effect mobility and lower effective electron mass, indicating its potential for higher stability. Therefore, spinel IGZO is an interesting alternative to amorphous and CAAC phase IGZO.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Physics, Applied
Md Rezaul Karim, Brenton A. Noesges, Benthara Hewage Dinushi Jayatunga, Menglin Zhu, Jinwoo Hwang, Walter R. L. Lambrecht, Leonard J. Brillson, Kathleen Kash, Hongping Zhao
Summary: The research has determined the valence band offset between ZnGeN2 and GaN, providing new insights and methods for device designs based on the III-N/ZnGeN2 heterostructure.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Environmental
Xuqing Zhang, Yongping Pu, Yating Ning, Bo Wang, Lei Zhang, Xian Zhang, Yangchao Shang, Zhemin Chen
Summary: This study demonstrates the possibility of achieving high energy storage density and efficiency in dielectric materials through appropriate preparation methods, and improving their breakdown strength and insulation performance. The introduction of Sm3+ and control of oxygen vacancy production effectively enhance the performance and stability of the material.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Physics, Applied
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Sergei Stepanoff, Aman Haque, Douglas E. Wolfe, Fan Ren, S. J. Pearton
Summary: NiO/Ga2O3 heterojunction rectifiers were irradiated with 1 Mrad of Co-60 gamma-rays, resulting in a 1000x reduction in forward current, a 100x increase in reverse current, and a significant decrease in the on-off ratio. The carrier concentration in the Ga2O3 drift region slightly decreased, indicating a reversible effect. The rectifiers showed no permanent ionizing dose effects and resistance to displacement damage, suggesting potential applications in harsh radiation environments with appropriate bias sequences.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Coatings & Films
Jian-Sian Li, Xinyi Xia, Chao-Ching Chiang, David C. C. Hays, Brent P. P. Gila, Valentin Craciun, Fan Ren, S. J. Pearton
Summary: The characteristics of sputtered NiO for pn heterojunctions with Ga2O3 were investigated, and it was found that the oxygen/nickel and Ni2O3/NiO ratios, as well as the bandgap and resistivity, increased with the O-2/Ar gas flow ratio. However, the bandgap and Ni2O3/NiO ratio decreased with increasing annealing temperature, resulting in higher film density. The incorporation of hydrogen into NiO during plasma exposure was confirmed, and the band alignments of NiO films with both alpha- and beta-Ga2O3 were determined to have type II-staggered gaps. The breakdown voltage of NiO/beta-Ga2O3 heterojunction rectifiers also varied with the O-2/Ar flow ratio during deposition.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
Benjamin C. Letson, Simon Barke, Peter Wass, Guido Mueller, Fan Ren, Stephen J. Pearton, John W. Conklin
Summary: The laser interferometer space antenna (LISA), a joint ESA and NASA project, will enable space-based gravitational wave detection. Three identical spacecraft will form a triangular configuration, flying in a drag-free formation around free-falling test masses. To compensate for test mass charging, UV photons with higher energy than gold's work function are needed. The performance of UV light emitting diodes (LEDs) for the LISA mission was characterized under various operating conditions, and degradation was found to be faster at elevated temperatures and in dc conditions. Preselection based on initial spectral ratio and ideality factor showed positive correlation with subsequent reliability. The UV LEDs for LISA are required to support a 2-year cruise and commissioning period, followed by a 4-year science mission.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
A. Y. Polyakov, A. I. Kochkova, Amanda Langorgen, Lasse Vines, A. Vasilev, I. V. Shchemerov, A. A. Romanov, S. J. Pearton
Summary: The study investigates the relationship between the emission rate of deep traps called E1 traps and the electric field dependence. The results demonstrate that the activation energy of the centers and the ratio of high-field to low-field electron emission rates follow a linear relationship with the square root of electric field at a fixed temperature, indicating the deep donor behavior of these traps. The possible microscopic nature of these centers is discussed based on recent theoretical calculations, and the most likely candidates are proposed to be Si-Ga1-H or Sn-Ga2-H complexes.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Review
Materials Science, Multidisciplinary
Benjamin C. Letson, John W. Conklin, Peter Wass, Simon Barke, Guido Mueller, Md Abu Jafar Rasel, Aman Haque, Stephen J. Pearton, Fan Ren
Summary: There are various applications for deep UV AlGaN Light-Emitting Diodes (LEDs), including virus inactivation, air and water purification, sterilization, bioagent detection, and UV polymer curing. The long-term stability of these LEDs is important for space missions such as the Laser Interferometer Space Antenna (LISA). The literature review shows that the decline in output power of these LEDs over extended operating times is mainly driven by current and temperature, with the degradation rate dependent on the cube of drive current density and exponentially on temperature. The main mechanism for this decline is believed to be the creation/migration of point defects. Pre-screening based on the ratio of band edge-to-midgap emission and LED ideality factor can identify devices with long lifetimes (>10,000 h).
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Crystallography
Jian-Sian Li, Hsiao-Hsuan Wan, Chao-Ching Chiang, Xinyi Xia, Timothy Jinsoo Yoo, Honggyu Kim, Fan Ren, Stephen J. Pearton
Summary: Vertical heterojunction rectifiers with p-type NiO and thick Ga2O3 drift layers grown on Sn-doped β-Ga2O3 substrates exhibited breakdown voltages > 8 kV. Low drift doping concentration, low power during NiO deposition, and the formation of a guard ring were key factors for achieving excellent performance. These results demonstrate the potential of NiO/Ga2O3 rectifiers beyond SiC and GaN.
Article
Engineering, Electrical & Electronic
Sergei P. Stepanoff, Aman Haque, Fan Ren, Stephen Pearton, Douglas E. Wolfe
Summary: The susceptibility of electronics to radiation increases as the size and complexity of electronic chips or systems increase. This study develops an indirect technique to identify radiation-susceptible regions and demonstrates its effectiveness in rapid detection.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Chemistry, Physical
Chao-Ching Chiang, Xinyi Xia, Jian-Sian Li, Fan Ren, S. J. Pearton
Summary: The 8-polytype of Ga2O3 is a promising material for next generation power electronics and solar-blind UV photodetectors due to its high critical electric field strength and ability to be grown as large diameter single crystals. Dry etching is being focused on for patterning such devices, but it may cause surface modification and damage to the material. This study demonstrates that dry etch damage in 8-Ga2O3 leads to a reduction in near-surface carrier concentration, affecting device parameters like on-state resistance and introducing trap-assisted space-charge-limited conduction in the damaged layers.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Xinyi Xia, Chao-Ching Chiang, Hsiao-Hsuan Wan, Fan Ren, Jihyun Kim, S. J. Pearton
Summary: Neutrons generated by charge-exchange reactions were used to irradiate Schottky Ga2O3 rectifiers and NiO/Ga2O3 p-n heterojunction rectifiers. The breakdown voltage was improved for Schottky rectifiers but highly degraded for their NiO/Ga2O3 counterparts. The switching characteristics were degraded for both types of devices after irradiation.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Hsiao-Hsuan Wan, Fan Ren, S. J. Pearton
Summary: Large area vertical NiO/β n-Ga2O/n(+) Ga2O3 heterojunction rectifiers with high breakdown voltage (3.6 kV) and large conducting currents (4.8 A) are demonstrated. The performance exceeds the unipolar 1D limit for GaN, indicating the potential of β-Ga2O3 for future high-power rectification devices. The breakdown voltage is strongly dependent on the carrier concentration in the drift region.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Crystallography
Jian-Sian Li, Hsiao-Hsuan Wan, Chao-Ching Chiang, Fan Ren, Stephen J. Pearton
Summary: The stability of vertical geometry NiO/Ga2O3 rectifiers was examined under two types of annealing. It was found that annealing at 300 degrees C resulted in the best performance, including maximizing breakdown voltage and on-off ratio, lowering forward turn-on voltage, reducing reverse leakage current, and maintaining on resistance. The surface morphology remained smooth and the NiO exhibited a bandgap of 3.84 eV with an almost unity Ni2O3/NiO composition.
Article
Crystallography
Chao-Ching Chiang, Jian-Sian Li, Hsiao-Hsuan Wan, Fan Ren, Stephen J. Pearton
Summary: Ga2O3 heterojunction rectifiers with NiO as the solution on the p-type side have become a novel candidate for power conversion applications. In this study, the optimized design of high-breakdown NiO/Ga2O3 rectifiers was examined using the Silvaco TCAD simulator to determine the electric field distribution. The doping concentration, guard ring thickness, and extension beyond the anode were all important factors in determining the breakdown location. The transition phenomenon from the edge of the NiO extension to the top contact periphery was found to be correlated with the depletion effect.
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Hsiao-Hsuan Wan, Fan Ren, S. J. Pearton
Summary: NiO/β-Ga2O3 vertical rectifiers show near-temperature-independent breakdown voltages (V-B) of >8 kV at 600 K. The power figure of merit (V-B)²/R-ON for 100 μm diameter devices is 9.1 GW cm(-2) at 300 K and 3.9 GW cm(-2) at 600 K. In contrast, Schottky rectifiers on the same wafers have V-B of about 1100 V at 300 K with a negative temperature coefficient of breakdown. The power figure of merit for Schottky rectifiers is much lower compared to the heterojunction rectifiers. The results demonstrate the potential of using transparent oxide heterojunctions for high temperature, high voltage applications.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Review
Engineering, Electrical & Electronic
S. J. Pearton, Xinyi Xia, Fan Ren, Md Abu Jafar Rasel, Sergei Stepanoff, Nahid Al-Mamun, Aman Haque, Douglas E. Wolfe
Summary: Wide bandgap semiconductors SiC and GaN are used in power electronics and light-emitting diodes. They have higher radiation hardness compared to Si devices due to larger threshold energies for creating defects and high rates of defect recombination. However, heavy-ion-induced catastrophic burnout commonly occurs in SiC and GaN power devices. Light-emitting devices are not affected by this mechanism. Strain has also been identified as a parameter affecting radiation susceptibility of wide bandgap devices.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Engineering, Electrical & Electronic
Chao-Ching Chiang, Hsiao-Hsuan Wan, Jian-Sian Li, Fan Ren, Timothy Jinsoo Yoo, Honggyu Kim, S. J. Pearton
Summary: Sputtered p-NiO films were used to suppress gate leakage and produce a positive shift in the gate voltage of AlGaN/GaN high-electron mobility transistors for e-mode operation. The utility of NiO gates in increasing the on-off ratio and shifting the threshold voltage in comparison to Schottky gates was demonstrated.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)