Article
Chemistry, Physical
Hui Guo, Pengfei Shao, Changkun Zeng, Haineng Bai, Rui Wang, Danfeng Pan, Peng Chen, Dunjun Chen, Hai Lu, Rong Zhang, Youdou Zheng
Summary: In this paper, the effects of a thin in-situ SiNx layer on GaN-based metal-insulator-semiconductor high electron mobility transistors were investigated. It was found that using in-situ SiNx as an interface sacrificial layer improved the electrical properties of the transistors. A trap model at the SiNx/AlGaN interface was proposed and experimentally confirmed.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Jiaqi He, Kangyao Wen, Peiran Wang, Minghao He, Fangzhou Du, Yang Jiang, Chuying Tang, Nick Tao, Qing Wang, Gang Li, Hongyu Yu
Summary: This work utilizes interface charge engineering to fabricate normally off metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs). The combination of in situ SiNx passivation and an O-3-treated Al2O3/AlGaN gate interface allows the device to provide excellent performance, including high breakdown voltage and low specific on-resistance. Additionally, a physical model of fixed charges at the Al2O3/AlGaN interface is established, elucidating the O-3-treated fixed-charge modulation mechanism.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Jiaqi He, Qing Wang, Guangnan Zhou, Wenmao Li, Yang Jiang, Zepeng Qiao, Chuying Tang, Gang Li, Hongyu Yu
Summary: Normally-off AIGaN/GaN MIS-HEMTs with high threshold voltage, low on-resistance and low threshold voltage hysteresis have been achieved by an improved regrowth technique with in-situ SiNx passivation. The devices utilize thin-barrier heterojunction to decrease the 2DEG underneath the gate and employ regrown Al0.2Ga0.8N and in-situ SiNx to recover 2DEG at the access regions and reduce contact resistance. The MIS-HEMTs also feature damage-free recessed-gate structures with in-situ SiNx as passivation and gate dielectric, contributing to high V-th uniformity and channel mobility, low on-resistance and hysteresis.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Biochemistry & Molecular Biology
Hsien-Chin Chiu, Chia-Hao Liu, Chong-Rong Huang, Chi-Chuan Chiu, Hsiang-Chun Wang, Hsuan-Ling Kao, Shinn-Yn Lin, Feng-Tso Chien
Summary: By growing a high-quality Al2O3/AlN layer in an HEMT, the MIS-HEMT showed improved gate leakage and threshold voltage compared to the SG-HEMT, achieving a higher turn-on voltage, better reliability, and longer lifetime.
Article
Physics, Applied
Zhanyong Xing, Haochen Zhang, Yue Sun, Lei Yang, Kunpeng Hu, Kun Liang, Dawei Wang, Houqiang Fu, Haiding Sun
Summary: In this work, an enhancement-mode (E-mode) AlGaN/GaN-based high-electron-mobility transistor (HEMT) with a graded AlGaN cap layer (GACL) is proposed. The GACL is designed to produce high-concentration polarization-induced holes and negative net polarization charges to benefit the normally-OFF operation of the device. The optimized graded-AlGaN-gated metal-semiconductor HEMT achieves a large threshold voltage of 4 V, and shortening the gate length and inserting an oxide layer can suppress gate leakage current and enhance gate voltage swing.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Young Jun Yoon, Jae Sang Lee, In Man Kang, Eun Je Lee, Dong-Seok Kim
Summary: MIS-HEMTs based on AlGaN/GaN heterojunctions were fabricated with a SiN passivation layer, and the effects of proton irradiation on device characteristics were studied. The device with Si-rich SiN passivation showed less variation in current characteristics after proton irradiation, indicating higher reliability and enhanced performance compared to the N-rich SiN device.
RESULTS IN PHYSICS
(2021)
Article
Chemistry, Physical
Guanjie Li, Xiaomin Li, Xinke Liu, Anran Gao, Junliang Zhao, Fawang Yan, Qiuxiang Zhu
Summary: In this work, Hf0.5Zr0.5O2 (HZO) fluorite was designed as a ferroelectric gate layer for normally-off HEMTs, and an HZO/MgO/AlGaN/GaN/Si ferroelectric-semiconductor heterostructure was constructed. The heterostructure exhibited high threshold voltage, good device electrical stability, and great semiconductor process compatibility on AlGaN/GaN.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Hui Guo, Pengfei Shao, Haineng Bai, Jian Zhou, Yanghu Peng, Songlin Li, Zili Xie, Bin Liu, Dunjun Chen, Hai Lu, Rong Zhang, Youdou Zheng
Summary: This paper systematically investigates the static properties and gate current mechanism of low-pressure chemical vapor deposition-SiNx/AlGaN/GaN metal-insulator-semiconductor-high-electron-mobility-transistor (MIS-HEMTs) at cryogenic temperature. The experiments show that the threshold voltage of the device shifts positively at low temperature, and both the maximum transconductance and ON-resistance are improved. The gate leakage mechanism transitions with increasing forward gate bias, from trap-assisted tunneling to Fowler-Nordheim tunneling at temperature below 150 K, and from Poole-Frenkel emission to Fowler-FN tunneling at temperature above 150 K.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Yutao Cai, Yuanlei Zhang, Ye Liang, Ivona Z. Mitrovic, Huiqing Wen, Wen Liu, Cezhou Zhao
Summary: Novel AlGaN/GaN MIS-HEMTs with a ZrOx charge trapping layer show low ON-state resistance and high breakdown voltage. TCAD simulation results demonstrate the charge trapping and de-trapping behaviors.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Computer Science, Information Systems
Dai-Jie Lin, Chih-Kang Chang, Kuntal Barman, Yu-Chuan Chu, William Shih, Jian-Jang Huang
Summary: A dual-gate high-electron-mobility transistor (HEMT) is proposed to enhance reverse conduction, achieving lower reverse conduction power loss in power applications such as synchronous DC-DC converters and inverters. This is due to a freewheeling path between the drain electrode and the auxiliary gate, facilitating effective dissipation of stored charges.
Article
Computer Science, Information Systems
Xiaoyu Ding, Xu Yuan, Tao Ju, Guohao Yu, Bingliang Zhang, Zhongkai Du, Zhongming Zeng, Baoshun Zhang, Xinping Zhang
Summary: A technique called ion implantation was used to passivate p-GaN and create a normally off p-GaN/AlGaN/GaN HEMT. Through experiments, it was determined that an ion implantation energy of 20 keV and a dosage of 1.5 x 10(13) cm(-2) were required for passivation. Annealing at 400 degrees C was found to be ideal for obtaining a normally off p-GaN HEMT with desirable electrical properties.
Article
Engineering, Electrical & Electronic
Guanjun Jing, Xinhua Wang, Sen Huang, Qimeng Jiang, Kexin Deng, Yuhao Wang, Yankui Li, Jie Fan, Ke Wei, Xinyu Liu
Summary: The linearity of AlGaN/GaN HEMTs can be effectively improved by utilizing LPCVD-SiNx passivation, especially at high current levels and temperatures.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Wen Shi, Qimeng Jiang, Tiantian Luan, Sen Huang, Xinhua Wang, Fuqiang Guo, Yixu Yao, Kexin Deng, Lan Bi, Jie Fan, Haibo Yin, Ke Wei, Wenjuan Xiong, Yankui Li, Haojie Jiang, Junfeng Li, Xinyu Liu
Summary: In this study, enhancement-mode GaN-based MIS-HEMTs were fabricated using RTCVD SiNx gate dielectric and PEALD SiNx interfacial layer, showing low V-TH hysteresis and interface trap density, confirming the improvement of interface quality through various measurements.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Analytical
Xiaohui Gao, Hui Guo, Rui Wang, Danfeng Pan, Peng Chen, Dunjun Chen, Hai Lu, Rong Zhang, Youdou Zheng
Summary: This paper investigates the use of SiNx film deposited by plasma-enhanced chemical vapor deposition as a gate dielectric in AlGaN/GaN HEMTs. The NH3 flow during SiNx deposition is found to significantly affect the device performance. By optimizing the NH3 flow and performing an in situ N-2 plasma surface treatment, the DC performances of MIS-HEMTs can be greatly improved, demonstrating the potential for PECVD-SiNx as a gate dielectric in GaN-based MIS-HEMTs.
Article
Computer Science, Information Systems
Xiaodong Zhang, Xing Wei, Peipei Zhang, Hui Zhang, Li Zhang, Xuguang Deng, Yaming Fan, Guohao Yu, Zhihua Dong, Houqiang Fu, Yong Cai, Kai Fu, Baoshun Zhang
Summary: This study investigates the variation of threshold voltage in AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with a SiNx/SiON composite gate dielectric on Si substrates. The results show that the MIS-HEMTs with the SiNx/SiON composite gate dielectric exhibit superior threshold voltage uniformity and smaller threshold voltage hysteresis compared to the reference device with only SiNx gate dielectric. The study also confirms that the variation of device threshold voltage is mainly related to trapping process by the interface states.
Article
Chemistry, Physical
Qingzhong Gui, Zhen Wang, Zhaofu Zhang, Liu Xie, Xiaoming Zha, Jun Wang, Yuzheng Guo
Summary: In this study, a category of 2D materials called graphenelike monolayer monoxides, monochlorides, and mononitrides (GLMMs) are systematically studied using density functional theory and density functional perturbation theory. The stability of different native point defects in GLMMs is investigated energetically, showing their outstanding structural stability and high resistance to vacancy formation. The dielectric properties of GLMMs are explored and found to be promising for device applications.
CHEMISTRY OF MATERIALS
(2023)
Article
Physics, Applied
Jiaqi Chen, Zhaofu Zhang, Yuzheng Guo, John Robertson
Summary: The structural, electronic, and optical properties of nine different polymorphs of silica are investigated using both the GGA and hybrid functional methods. Similar crystal structures share analogous electronic and optical features, except for the stishovite phase. Linear relationships are established between the bandgap and static dielectric constant, as well as between refractive indices and densities. The sX functional accurately reproduces experimental bandgap values, while GGA is superior for overall optical property trends.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Hailing Guo, Yinheng Yin, Wei Yu, John Robertson, Sheng Liu, Zhaofu Zhang, Yuzheng Guo
Summary: The performance limits of sub-5 nm InSe and In2SSe MOSFETs were explored through quantum transport simulations. Van der Waals heterostructures assembled with different 2D materials have emerged as a new design of artificial materials with promising physical properties. Device performance was investigated using InSe/In2SSe van der Waals heterostructure as the channel material, with the heterostructure transistor showing higher on-state current and faster switching speed compared to isolated monolayer transistors.
Article
Physics, Applied
Jinhao Su, Zhaofu Zhang, Xuhao Wan, Wei Yu, Anyang Wang, Hongxia Zhong, John Robertson, Yuzheng Guo
Summary: By using the density functional theory and ab initio molecular dynamics simulations, this study investigates the structural, electronic, and optical properties of Sb-rich amorphous Ge3Sb6Te5. The results demonstrate that excess Sb concentration enhances the structural stability and improves the electrical and optical property contrast between crystalline and amorphous phases. These findings provide a theoretical basis for utilizing Sb-rich Ge3Sb6Te5 in prolonged service.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Chunmin Cheng, Zhaofu Zhang, Xiang Sun, Qingzhong Gui, Gai Wu, Fang Dong, Dongliang Zhang, Yuzheng Guo, Sheng Liu
Summary: Diamond electronic devices have gained attention for high power and high frequency applications. The interface between metal and diamond is crucial for device performance, with Schottky barrier heights (SBHs) playing a significant role. This study investigates metal-induced gap states (MIGS) at the diamond (111) interface using first-principles calculations. The results show larger transverse tunneling probability and smaller longitudinal tunneling probability for all diamond contact interfaces. Low work function metals such as Sc and Ti generate higher SBHs (-1.0 eV +/- 0.6 eV), while Pt and Ni have a smaller barrier height of -0.5 eV, making them suitable for low contact resistance ohmic electrodes. The calculated SBHs are consistent with experimental findings. This work provides insights into the electrical structural changes at the metal-diamond contact interface and aids in selecting suitable electrodes for high-power diamond devices.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Shumeng Yan, Yu Zhou, Jianxun Liu, Yaozong Zhong, Xiujian Sun, Xin Chen, Xiaolu Guo, Qian Li, Qian Sun, Hui Yang
Summary: The influence of energy band structure on the electrical characteristics of GaN-based DHBTs was studied through simulation and fabrication. A novel DHBT structure with a composition graded base was grown and fabricated, achieving a long minority carrier lifetime of 4.08 ns. The elimination of the energy barrier at the conventional GaN/InGaN/GaN B-C junction interface was proposed by combining indium composition grading of the p-InGaN base layer and Si doping profile tuning for the collector layer. The as-fabricated DHBT presented a high intercept voltage of 225 V and a high current gain of 49.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Chemistry, Multidisciplinary
Juntong Chen, Jianxun Liu, Yingnan Huang, Ruisen Liu, Yayu Dai, Leming Tang, Zheng Chen, Xiujian Sun, Chenshu Liu, Shuming Zhang, Qian Sun, Meixin Feng, Qiming Xu, Hui Yang
Summary: Heteroepitaxial growth of high Al-content AlGaN often leads to threading dislocations and surface hexagonal hillocks, which degrade the performance and reliability of AlGaN-based UVC LEDs. This study investigates the degradation mechanism and impurity/defect behavior of UVC LEDs in relation to the hexagonal hillocks. Electron leakage is found to be the main cause of early degradation in UVC LEDs. The role of hillock edges in electron leakage is confirmed by transmission electron microscopy measurements, time-of-flight secondary ion mass spectrometry, and conductive atomic force microscopy. Dislocations bunching and segregation of impurities at the hillock edges facilitate trap-assisted carrier tunneling and recombination in the p-AlGaN. This work provides insights into a possible degradation mechanism of AlGaN-based UVC LEDs.
Article
Chemistry, Multidisciplinary
Wenbo Li, Leming Tang, Yong Yang, Zhicong Zhang, Guanghui Li, Meixin Feng, Qiming Xu, Qian Sun
Summary: In this study, thin-fluorine-resin-film-packaged deep-ultraviolet light-emitting diodes (DUV LEDs) were fabricated by the drip-coating method and tested for their characteristics. The results showed that the light output power increased from 4.95 mW to 5.44 mW at 40 mA, and the cost of fluorine resin could be reduced to about 10%. Furthermore, no degradation was observed during aging. However, >10% decay was observed after aging for 1000 h when the light output power reached 12 mW or higher. In conclusion, thin-fluorine-resin-film-packaged DUV LEDs can achieve a 10% enhancement in light output power by using less fluorine resin material, and the material is more applicable to low-power DUV LEDs.
APPLIED SCIENCES-BASEL
(2023)
Article
Crystallography
Yingnan Huang, Jianxun Liu, Xiujian Sun, Xiaoning Zhan, Qian Sun, Hongwei Gao, Meixin Feng, Yu Zhou, Hui Yang
Summary: We report on the epitaxial lateral overgrowth (ELO) of high-quality AlN on stripe-patterned Si(111) substrates with various trench widths. By narrowing down the trench and ridge widths of patterned Si substrates, crack-free, 6-micrometer-thick, high-quality AlN films on Si substrates were produced. This work paves the way for the fabrication of high-performance Al(Ga)N-based thin-film devices on Si.
Article
Computer Science, Information Systems
Yuan Ji, Sen Huang, Qimeng Jiang, Ruizhe Zhang, Jie Fan, Haibo Yin, Yingkui Zheng, Xinhua Wang, Ke Wei, Xinyu Liu
Summary: The non-recessed ohmic contact resistance on ultrathin-barrier AlGaN/GaN heterostructure was effectively reduced to 0.16 Omega.mm using the 'ohmic-before-passivation' process. The recovery of 2-D Electron Gas adjacent to the ohmic contact was enhanced by a composite double-layer dielectric with AlN/SiNx passivation. Thermionic field emission was identified as the dominant ohmic contact mechanism. The optimized ohmic contact achieved low on-resistance and high current density, making it a promising strategy for optimizing low-voltage GaN-based power devices.
Article
Engineering, Electrical & Electronic
Qingzhong Gui, Wei Yu, Chunmin Cheng, Hailing Guo, Xiaoming Zha, John Robertson, Sheng Liu, Zhaofu Zhang, Yuzheng Guo
Summary: This study investigates the properties of hexagonal beryllium oxide/(H, O-Si)-diamond heterostructures and finds that they exhibit better performance compared to fluorine- and oxygen-terminated ones, making them a high-quality gate dielectric material for diamond devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Applied
Zhiyong Fu, Hailing Guo, Xiting Wang, Ruyue Cao, Hongxia Zhong, Sheng Liu, John Robertson, Yuzheng Guo, Zhaofu Zhang
Summary: The combined feature of high thermal conductivity and high carrier mobility makes cubic boron arsenide (c-BAs) promising for high power and high frequency applications. The interfacial contact effects of BAs (110), (111), and (100) surfaces with various metals have been studied using first-principles calculations. The results provide insights into the properties at metal-BAs contact interfaces and offer a theoretical basis for the selection of suitable electrodes for high power BAs devices.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Wei Yu, Zhaofu Zhang, Xuhao Wan, Hailing Guo, Qingzhong Gui, Yuan Peng, Yifei Li, Wenjie Fu, Dingyi Lu, Yuchen Ye, Yuzheng Guo
Summary: Density functional theory (DFT) is a powerful computational tool for electronic structure calculations of materials. DFT + U + V is an alternative approach that can overcome the limitations of accuracy and efficiency. In this study, we propose the use of Bayesian optimization with a dropout (BOD) algorithm to optimize the U and V terms, resulting in improved electronic properties for bulk materials at a lower computational cost. We also observe that U/V parameters are reasonably transferable between surface slabs and interfaces, allowing for accurate electronic property calculations of large-scale systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Xuhao Wan, Zhaofu Zhang, Anyang Wang, Jinhao Su, Wenjun Zhou, John Robertson, Yuan Peng, Yu Zheng, Yuzheng Guo
Summary: Exploring a new generation of eco-friendly gas insulation medium to replace SF6 in power industry is significant for reducing the greenhouse effect and building a low-carbon environment. The gas-solid compatibility of insulation gas with various electrical equipment is also of significance before practical applications. The study proposes a strategy to evaluate the gas-solid compatibility between CF3SO2F and the typical solid surfaces of equipment and provides theoretical and experimental evidence for its validity.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Rong Han, Zhaofu Zhang, Wei Liu, Fengxiang Ma, Hailing Guo, Zhuo Jiang, Xuhao Wan, Anyang Wang, Chao Yuan, Wenjun Zhou, Yu Zheng, Yuzheng Guo
Summary: Designing prominent gas sensor materials for the detection of environmentally friendly insulating gas C4F7N decomposition products is an effective strategy. The gas sensing performance of 2D-Ga2O3 towards C4F7N decomposition products has been evaluated, showing its selectivity, sensitivity, stability, and adsorption strength. Biaxial strain engineering is an important pathway to adjust the adsorption energy and sensitivity of 2D-Ga2O3 towards C3F6.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
