Review
Crystallography
Nethala Manikanthababu, Hardhyan Sheoran, Pradeep Siddham, Rajendra Singh
Summary: This review investigates the effects of radiation on beta-Ga2O3 material and devices and explores its potential applications in power electronics. The study summarizes various studies on radiation-induced effects on the structure and performance of beta-Ga2O3 devices. It also highlights the importance of understanding pre-existing defects and radiation-induced defects in device performance. The results suggest that beta-Ga2O3-based devices could be suitable for space or high-radiation terrestrial applications.
Review
Physics, Applied
Chao Lu, Xueqiang Ji, Zeng Liu, Xu Yan, Nianpeng Lu, Peigang Li, Weihua Tang
Summary: This review summarizes recent research progress on beta-Ga2O3-metal contacts, including related theories, measurements, fabrication processes, and control methods. These studies provide important insights for both theoretical understanding of the metal/semiconductor interface and the fabrication process for engineering applications of Ga2O3-based devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Caixia Hou, Rodrigo M. Gazoni, Roger J. Reeves, Martin W. Allen
Summary: This study reports a significant improvement in the rectifying performance of Pd Schottky contacts on β-Ga2O3 at high temperatures in air, leading to similar thermal characteristics as diamond and SiC contacts at 500 degrees C. The increase in rectifying performance is attributed to the oxidation of the Pd SC layer, creating higher barrier height PdO regions that dominate high-temperature current transport. Additionally, good agreement was observed between the temperature dependence of the built-in voltage of the thermally oxidized Pd SCs and the optical bandgap of β-Ga2O3.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Electrochemistry
Qingyuan Zhang, Dawei Gu, Hui Li, Ze Xu, Hongshun Sun, Jishu Li, Lei Wang, Linjiang Shen
Summary: In this study, RuO2 was deposited on Ta substrates and assembled into supercapacitors RuO2//RuO2, whose output energies under dynamic conditions were evaluated. The results showed that a decrease in the mass of the negative electrode could enhance the energy of RuO2//RuO2.
ELECTROCHIMICA ACTA
(2021)
Article
Chemistry, Physical
E. B. Yakimov, A. Y. Polyakov, I. V. Shchemerov, N. B. Smirnov, A. A. Vasilev, A. I. Kochkova, P. S. Vergeles, E. E. Yakimov, A. V. Chernykh, Minghan Xian, F. Ren, S. J. Pearton
Summary: Lightly n-type doped Ga2O3 layers grown by Halide Vapor Phase Epitaxy (HVPE) on bulk n(+)-Ga2O3 substrates were treated with fast reactor neutrons, 20 MeV protons, or high ion density Ar plasma, leading to an increase in deep acceptors concentration. This resulted in a significant enhancement of photocurrent and EBIC current collection efficiency in Schottky diodes on the layers, potentially improving the photosensitivity of Ga2O3-based solar-blind photodetectors.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Youn-Hye Kim, Minsu Kim, Yohei Kotsugi, Taehoon Cheon, Debananda Mohapatra, Yujin Jang, Jong-Seong Bae, Tae Eun Hong, Rahul Ramesh, Ki-Seok An, Soo-Hyun Kim
Summary: ALD-RuO2 film with optimal process conditions shows excellent growth behavior and diffusion barrier performance, effectively preventing interdiffusion of Ru and Si.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Materials Science, Coatings & Films
Luke A. M. Lyle, Kunyao Jiang, Elizabeth V. Favela, Kalyan Das, Andreas Popp, Zbigniew Galazka, Guenter Wagner, Lisa M. Porter
Summary: The Schottky barriers of Ti, Mo, Co, Ni, Pd, and Au on (100) beta-Ga2O3 substrates were analyzed using a combination of J-V, C-V, and J-V-T measurements. The results revealed a strong positive correlation between the calculated Schottky barrier heights and the metal work functions.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Chemistry, Physical
Philipp Wendel, Dominik Dietz, Jonas Deuermeier, Andreas Klein
Summary: ZnO/RuO2 Schottky diodes prepared by magnetron sputtering exhibit reversible hysteresis behavior in their current-voltage characteristics, with the Schottky barrier height varying between 0.9 and 1.3 eV during voltage cycling. This variation is attributed to trapping and de-trapping of electrons in oxygen vacancies.
Review
Engineering, Electrical & Electronic
Hardhyan Sheoran, Vikram Kumar, Rajendra Singh
Summary: This study comprehensively reviews the recent development of metal-semiconductor contacts on ultrawide bandgap beta-gallium oxide (beta-Ga2O3). The study starts by introducing the basic concepts of metal-semiconductor contacts and then summarizes the current literature on ohmic and Schottky contacts on beta-Ga2O3. Finally, the status of high-power Schottky diode contact on beta-Ga2O3 is presented.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Crystallography
Maolin Zhang, Zeng Liu, Lili Yang, Jiafei Yao, Jing Chen, Jun Zhang, Wei Wei, Yufeng Guo, Weihua Tang
Summary: This review article summarizes recent advances in the experimental and theoretical research on β-Ga2O3-based power devices, providing comprehensive guidance for further development by discussing the operating mechanisms and obstacles to be addressed.
Article
Nanoscience & Nanotechnology
Ping-Feng Chi, Feng-Wu Lin, Ming-Lun Lee, Jinn-Kong Sheu
Summary: This article demonstrates solar-blind photodetectors composed of Ga2O3/p-GaN bipolar heterojunctions formed through thermal oxidation and silicon ion implantation processes. The experimental results show that the thermal oxidation process converts p-GaN into semi-insulating β-Ga2O3 films, while silicon ion implantation transforms the insulating properties into n-type β-Ga2O3 with low resistivity and high electron concentration. The fabricated PDs exhibit high photoresponses in the solar-blind band.
Article
Nanoscience & Nanotechnology
Shiqi Yan, Teng Jiao, Zijian Ding, Xinyu Zhou, Xingqi Ji, Xin Dong, Jiawei Zhang, Qian Xin, Aimin Song
Summary: This study fabricates a Ti/Ga2O3/Au Schottky avalanche photodetector based on a β-Ga2O3 epitaxial film grown on a sapphire substrate through metal-organic chemical vapor deposition. The photodetector exhibits high responsivity, ultrahigh photo-to-dark current ratio, and high external quantum efficiency, indicating potential application for solar-blind imaging.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Hongbin Wang, Jiangang Ma, He Chen, Longpu Wang, Peng Li, Yichun Liu
Summary: In this study, self-powered solar-blind ultraviolet (UV) photodetectors (PDs) based on Ga2O3/ZnO:V heterojunction were fabricated using the pulsed laser deposition method. The photoresponse behaviors of the Ga2O3/ZnO:V PDs can be controlled by the induced ferroelectric polarization field in ZnO:V. The improved performance of the Ga2O3/ZnO:V PD can be attributed to the increase in the built-in electric field and the widening of the depletion region under the influence of the depolarization field, which benefits the separation and transport of photogenerated carriers at the heterojunction interface.
MATERIALS TODAY PHYSICS
(2023)
Article
Physics, Applied
Z. Dela Cruz, C. Hou, R. F. Martinez-Gazoni, R. J. Reeves, M. W. Allen
Summary: The performance of beta-Ga2O3 Schottky contacts (SCs) fabricated using amorphous, intentionally oxidized platinum-iridium alloys was investigated. The study found that Pt0.5Ir0.5Ox SCs had the highest Schottky barriers on all beta-Ga2O3 crystal faces, providing better contacts and lower reverse leakage currents. All PtyIr(1-y)Ox SCs on ( 2 over bar 01) beta-Ga2O3 showed excellent high-temperature performance.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Guanqi Li, Ruifan Tang, Na Gao, Cheng Li, Jinchai Li, Kai Huang, Junyong Kang, Rong Zhang
Summary: The research shows that devices fabricated with Au electrodes have lower dark current and higher photocurrent compared to those with Ti electrodes. Devices oxidized for 10 hours with Au electrodes exhibit solar-blind responsivity with a full width at half maxima of 12 nm, attributed to the thicker Ga2O3 film.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Chemistry, Physical
Alexandra R. McNeill, Rodrigo Martinez-Gazoni, Roger J. Reeves, Martin W. Allen, Alison J. Downard
Summary: ZnO is a strong candidate for transparent electronic devices due to its wide band gap and earth-abundance, but its practical use is limited by surface metallicity. Modification of ZnO single crystal surfaces with aryl films and NP films can decrease the downward surface band bending, with evidence of Zn-O-C bonding provided by XPS measurements.
Article
Engineering, Electrical & Electronic
Caixia Hou, Rodrigo M. Gazoni, Roger J. Reeves, Martin W. Allen
Summary: This study reports a significant improvement in the rectifying performance of Pd Schottky contacts on β-Ga2O3 at high temperatures in air, leading to similar thermal characteristics as diamond and SiC contacts at 500 degrees C. The increase in rectifying performance is attributed to the oxidation of the Pd SC layer, creating higher barrier height PdO regions that dominate high-temperature current transport. Additionally, good agreement was observed between the temperature dependence of the built-in voltage of the thermally oxidized Pd SCs and the optical bandgap of β-Ga2O3.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Physics, Applied
Chikezie C. Onyema, Roger J. Reeves, Martin W. Allen
Summary: MESFETs were fabricated on ZnO thin films grown via mist-CVD, using in situ intentionally oxidized AgOx SC gates to achieve high performance. These devices showed potential for producing low-cost, low operating voltage, transparent thin film transistors due to the significant increase in Schottky barrier height and passivation of oxygen vacancies at the gate-channel interface.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
Rodrigo F. Martinez-Gazoni, Martin W. Allen, Roger J. Reeves
Summary: The study investigated the persistent photoconductivity (PPC) of high-quality SnO2 (101) films grown by molecular beam epitaxy (MBE), showing that the longest duration was achieved under high-vacuum conditions, sensitivity to pressure changes, and the dominant role of water vapor. Increasing carrier concentration significantly increased the duration, while decreasing temperature led to a significant decrease in persistent photoconductivity.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Public, Environmental & Occupational Health
Marco Lee Solano, Samuel Robinson, Martin W. Allen, Gillian Reyes-Marcelino, David Espinoza, Brooke Beswick, Dorothy H. K. Tse, Liyang Ding, Lauren Humphreys, Cathelijne Van Kemenade, Suzanne Dobbinson, Amelia K. Smit, Anne E. Cust
Summary: Interactive educational activities using handheld dosimeters can improve primary school students' knowledge about UV radiation and sun protection. A study in Australia found that students had moderate knowledge about UV and sun protection, but their knowledge significantly improved after a short interactive educational activity using handheld UV dosimeters.
PREVENTIVE MEDICINE REPORTS
(2022)
Article
Physics, Applied
Z. Dela Cruz, C. Hou, R. F. Martinez-Gazoni, R. J. Reeves, M. W. Allen
Summary: The performance of beta-Ga2O3 Schottky contacts (SCs) fabricated using amorphous, intentionally oxidized platinum-iridium alloys was investigated. The study found that Pt0.5Ir0.5Ox SCs had the highest Schottky barriers on all beta-Ga2O3 crystal faces, providing better contacts and lower reverse leakage currents. All PtyIr(1-y)Ox SCs on ( 2 over bar 01) beta-Ga2O3 showed excellent high-temperature performance.
APPLIED PHYSICS LETTERS
(2022)
Article
Biochemistry & Molecular Biology
Sarah E. Cole, Makenzie Hawkins, Kimberly A. Miller, Martin W. Allen, Myles Cockburn
Summary: The incidence of melanoma is increasing, especially among Hispanics in California. Childhood exposure to ultraviolet radiation is found to significantly increase the risk of melanoma. A study conducted in Los Angeles County among Hispanic students in 4th and 5th grade classrooms revealed that wanting to get a tan was associated with less time spent outside, while sun protective knowledge and family discussion of sunscreen were associated with less time spent outside. Most of the UV exposure in this population occurred at school.
PHOTOCHEMISTRY AND PHOTOBIOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Jonty I. Scott, Ryan L. Adams, Rodrigo F. Martinez-Gazoni, Liam R. Carroll, Alison J. Downard, Tim D. Veal, Roger J. Reeves, Martin W. Allen
Summary: A highly scalable method for producing vertically aligned square-shaped Sb-doped SnO2 nanotubes has been reported using mist chemical vapor deposition. These nanotubes exhibit excellent structural quality and have potential applications in gas sensing and catalysis. Fabrication of square SnO2 nanotube diodes and field effect transistors has demonstrated their device potential.
Article
Engineering, Electrical & Electronic
Phuong Y. Le, Hilal Nagib, Luke A. Sylvander, Martin W. Allen, Dougal G. McCulloch, James G. Partridge, Hiep N. Tran
Summary: Volatile lateral memristors fabricated from amorphous SnO2 exhibit synaptic properties and can modulate conductance based on the characteristics of voltage pulses or UVC light. By combining light and voltage pulses, OR/AND logic functions can be achieved using a single device. The device behavior is affected by surface water chemisorption, but the functions are reliably demonstrated regardless of the ambient interaction. Simulation results suggest that these devices can enable hand-written digit recognition with over 90% accuracy when arranged in a suitable array.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Physical
Simon Astley, Di Hu, Kerry Hazeldine, Johnathan Ash, Rachel E. Cross, Simon Cooil, Martin W. Allen, James Evans, Kelvin James, Federica Venturini, David C. Grinter, Pilar Ferrer, Rosa Arrigo, Georg Held, Gruffudd T. Williams, D. Andrew Evans
Summary: Photoelectron spectroscopy is a powerful tool for characterizing semiconductor surfaces and interfaces. However, it is often limited to ultrahigh vacuum conditions and can only probe the top few atomic layers. Recent advances in instrumentation have addressed these limitations, enabling measurement at near-ambient pressures and real-time monitoring of surface processing. Nevertheless, there are still limitations due to irreversible chemical effects and reversible physical effects. This study demonstrates how real-time and near-ambient pressure photoelectron spectroscopy can be used to identify and quantify these effects.
FARADAY DISCUSSIONS
(2022)
Article
Engineering, Electrical & Electronic
Liam R. Carroll, Rodrigo F. Martinez-Gazoni, Nicola Gaston, Roger J. Reeves, Alison J. Downard, Martin W. Allen
Summary: The study investigates the covalent modification of beta-Ga2O3 surfaces with organic layers to control their surface band bending. The research shows that NP modification leads to upward band bending shifts while ODPA modification results in downward shifts in surface band bending. These findings provide valuable insights for the electronic applications of beta-Ga2O3.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
