Article
Physics, Applied
Qiang Liu, Marcin Zajac, Malgorzata Iwinska, Shuai Wang, Wenrong Zhuang, Michal Bockowski, Xinqiang Wang
Summary: Ethylene is an excellent carbon dopant source for the growth of semi-insulating GaN crystals by halide vapor phase epitaxy, with a doping efficiency much higher than methane. By ethylene doping, a record highest resistivity can be achieved.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Condensed Matter
Kenji Iso, Hirotaka Ikeda, Tae Mochizuki, Takafumi Odani, Satoru Izumisawa
Summary: A new method is proposed to fabricate semi-insulating GaN (SI-GaN) substrates by using a dual-layer structure, including approximately 100 μm-thick Fe, C, or Mn-doped GaN as the upper layer and approximately 300 μm-thick unintentionally doped GaN as the lower layer, via hydride vapor-phase epitaxy. Substrates doped with Fe, C, or Mn are successfully produced without cracks and pits, and the resistivities at room temperature reach up to 6.6 x 10^8, >10^12, and >10^12 Ω·cm, respectively, around a doping concentration of approximately 10^18 cm^(-3). The residual stress of the dual-layer SI-GaN film is also evaluated.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Physics, Applied
Hongyue Wang, Po-Chun (Brent) Hsu, Ming Zhao, Eddy Simoen, Stefan De Gendt, Arturo Sibaja-Hernandez, Jinyan Wang
Summary: The study investigates electrically active defects in carbon-doped GaN layers using a metal/carbon-doped GaN/Si-doped GaN MIS structure, revealing trap states associated with different carbon doping concentrations. This provides further insights into the impact of these defects on the electrical characteristics of GaN power devices.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Crystallography
Yun Lai, Ding Wang, Qinhao Kong, Xiaoju Luo, Jinfeng Tang, Rensuo Liu, Fei Hou, Xianying Wang, Troy J. Baker
Summary: Four-inch semi-insulating free-standing gallium nitride (GaN) wafers grown by hydride vapor phase epitaxy (HVPE) with carbon doping were obtained through a self-separated process. The as-grown wafer thickness can reach 900 mu m without cracks, and x-ray diffraction rocking curves show low FWHMs. The measured resistivity was greater than 10(10) Omega-cm.
JOURNAL OF CRYSTAL GROWTH
(2021)
Article
Chemistry, Physical
Mikolaj Amilusik, Marcin Zajac, Tomasz Sochacki, Boleslaw Lucznik, Michal Fijalkowski, Malgorzata Iwinska, Damian Wlodarczyk, Ajeesh Kumar Somakumar, Andrzej Suchocki, Michal Bockowski
Summary: The co-doping of manganese and carbon in gallium nitride crystals grown by halide vapor phase epitaxy was investigated in terms of their structural, optical, and electrical properties. The results showed the significant roles of manganese and carbon in the co-doped gallium nitride crystals.
Article
Physics, Applied
Daiki Tanaka, Kenji Iso, Jun Suda
Summary: In this study, electrical properties of semi-insulating GaN substrates doped with iron (Fe), carbon (C), or manganese (Mn) were investigated. The highest resistivity was observed in Mn-doped samples. Fe-doped samples showed n-type conduction, while C-doped samples and Mn-doped samples with a Mn concentration of 1 x 10(19) cm(-3) showed p-type conduction. Analysis of the carrier concentration showed that all dopants formed acceptor levels at specific energies for conduction.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
E. Belas, M. Betusiak, R. Grill, P. Praus, M. Brynza, J. Pipek, P. Moravec
Summary: We investigated carrier transport and space charge formation in high-purity semi-insulating 4H-SiC bulk single crystals. Using the Laser-induced Transient Current Technique, we observed anomalous short current waveform oscillations caused by very short carrier lifetimes. Through detailed analysis of the current waveform and collected charge, we concluded that the electron mobility decreases with increasing electric field. We also observed the blocking character of prepared Au contacts, inducing electron depletion and positive space charge formation. Our findings provide a theoretical model that describes the observed phenomena well.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Electrical & Electronic
Roman Stoklas, Ales Chvala, Peter Sichman, Stanislav Hasenohrl, Stefan Hascik, Juraj Priesol, Alexander Satka, Jan Kuzmik
Summary: Vertical current conduction in semi-insulating C-doped GaN grown on a GaN substrate was analyzed, showing different effects on electron conduction under varying C concentrations.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Materials Science, Multidisciplinary
Peter Sichman, Roman Stoklas, Stanislav Hasenohrl, Dagmar Gregusova, Milan Tapajna, Boris Hudec, Stefan Hascik, Tamotsu Hashizume, Ales Chvala, Alexander Satka, Jan Kuzmik
Summary: This study investigates vertical GaN transistors with a semi-insulating channel layer and a C doping of 1 x 10^17 cm(-3). The structures are grown using metal-organic chemical vapor deposition on conductive GaN substrates. The transistors demonstrate normally off behavior and an on/off ratio of 10^7 at a gate bias of -2 V, with an open channel drain current of 30 mA at a gate bias of 4 V.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Chemistry, Physical
Kang Zhang, Hualong Wu, Qiao Wang, Wei Zhao, Chengguo Li, Yuan Ren, Ningyang Liu, Longfei He, Chenguang He, Zhitao Chen
Summary: Interfacial engineering with a thin AlN buffer layer can effectively suppress dislocations and oxygen impurities in GaN epilayers, leading to a rapid decrease in TDD value and high-crystalline-quality SI materials.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Wei-Hsiang Huang, Chin-Jung Lin, Tsung-Han Huang, Chia-Yu Chang, Shu-Chih Haw, Hwo-Shuenn Sheu, Shih-Yun Chen, Chung-Li Dong, Krishna Kumar, Bing Joe Hwang, Wei-Nien Su, Chi-Liang Chen
Summary: In this study, Fe(III) ions were incorporated into TiO2 hollow submicrospheres, which served as an excellent photocatalyst. The experimental parameters such as flow rate, rotation speed, and contaminant concentration were found to improve the catalyst activity. Fe-TiO2 hollow submicrospheres with different Fe wt% were prepared, and it was discovered that 2.5 wt% Fe-TiO2 exhibited the best photocatalyst activity. The Fe(III) doping not only increased the interaction between transition metal (Fe and Ti) 3d orbitals in TiO2, but also promoted the Fe(III)/Fe(II) redox kinetics and the associated photo-Fenton degradation of acetaminophen.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Huifeng Li, Mingchun Li, Minggao Song, Peijie Wang, Zihan Ping, Guanyu Zhao, Yusheng Wu, Laishi Li
Summary: A novel Fe-doped BiOI nanosheet with surface attached Fe (III) clusters was fabricated via a facile hydrothermal method. The Fe-doped BiOI exhibited better photocatalytic performance compared to pure BiOI, with an upshift of the conduction band and effective inhibition of carrier recombination induced by Fe (III) clusters. The degradation efficiency of tetracycline by 8Fe-BiOI was greatly improved under Xe lamp irradiation.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Tsung-Shine Ko, En-Ting Lin, Yen-Teng Ho, Chen-An Deng
Summary: In this study, few-layer WS2 films were deposited on GaN and sapphire substrates to form heterojunctions. It was found that using GaN as a substrate effectively enhanced the SERS signal compared to sapphire. The analysis of different techniques revealed that the increased number of transition pathways in the interface between WS2 and GaN contributed to the enhanced SERS signal. The WS2/GaN heterostructure proposed in this study can serve as a reference for enhancing SERS efficiency.
Article
Materials Science, Ceramics
Li Hou, Lei Shi, Jiyin Zhao, Ruixue Tong, Shiming Zhou, Xianbing Miao, Yang Xin
Summary: The study systematically investigates the effects of Sm-doping on the crystal structure, dielectric, and magnetic properties of CeFeO3 ceramics. A giant dielectric response is observed in Ce0.5Sm0.5FeO3 compounds at room temperature, attributed to the increase in Fe2+/Fe3+ ionic contents due to charge transfer induced by Sm doping. The results suggest that a combination of ferromagnetic double-exchange interaction related to the Fe2+ ionic content and composite spin configurations of Fe3+ ions dominate the dielectric loss in Ce1-xSmxFeO3 ceramics.
CERAMICS INTERNATIONAL
(2021)
Article
Physics, Applied
C. Koller, L. Lymperakis, D. Pogany, G. Pobegen, C. Ostermaier
Summary: The presence of carbon impurities in GaN affects its semiconducting behavior. Experimental analysis supports the dominant acceptor model over the auto-compensation model. Extreme carbon-rich growth conditions may be necessary to explain the discrepancy between theoretical and experimental results.
JOURNAL OF APPLIED PHYSICS
(2021)
