Article
Engineering, Electrical & Electronic
He Guan, Liyi He, Jingbo Wu, Ziqiang Zeng, Yunshuo Li, Borui Deng, Guiyu Shen, Wentao Li, Yucheng Wang
Summary: A high-resistance Si-based AlInGaN/GaN heterojunction epitaxy with AlN/AlGaN buffer layers and AlInGaN barrier layer was successfully produced in this study, and a novel varistor was proposed based on this material. The varistor consists of a narrow groove etched into the GaN channel and metal electrodes attached to the epitaxy surface. The device exhibited typical varistor characteristics and the opening voltage could be adjusted by altering the groove width.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Shun Lu, Manato Deki, Jia Wang, Kazuki Ohnishi, Yuto Ando, Takeru Kumabe, Hirotaka Watanabe, Shugo Nitta, Yoshio Honda, Hiroshi Amano
Summary: The study demonstrated a fabrication process for Ohmic contact on low-doping-density p-type GaN with nitrogen-annealed Mg, achieving reduced contact resistance and a localized contact layer. The mechanism underlying the reduced contact resistance, involving mutual diffusion of Ga and Mg atoms on the interface, was studied using various techniques such as scanning transmission electron microscopy.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Nan Jin, Yugang Zhou, Yan Guo, Sai Pan, Rong Zhang, Youdou Zheng
Summary: This work presents the fabrication and analysis of high-reflectivity Ag nanodot (AgND)/Mg/Al Ohmic contacts on both p-GaN and n-GaN. The contacts showed low specific resistance and excellent thermal stability. X-ray photoelectron spectroscopy and x-ray diffraction measurements were conducted to investigate the contact mechanisms. The results suggest that this contact scheme can improve the density of GaN-based ICs and micro-LEDs, as well as enhance the light output efficiency of GaN-based LEDs.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Condensed Matter
Minglong Zhang, Masao Ikeda, Siyi Huang, Jianping Liu, Jianjun Zhu, Shuming Zhang, Hui Yang
Summary: The specific contact resistance rho(c) to p-GaN was measured for different structures of Ni/Pd-based metals and thin p-InGaN/p(+)GaN contacting layers. It was found that the metal containing Pd had approximately 35% lower rho(c) compared to single Ni. Thin p-InGaN contacting layers grown on p(+)-GaN layers showed significantly smaller values of rho(c) compared to p(+)-GaN without p-InGaN. The study also examined the current density dependence of rho(c) and achieved the lowest rho(c) of 4.9 x 10(-5) Omega.cm(2) @ J= 3.4 kA/cm(2).
JOURNAL OF SEMICONDUCTORS
(2022)
Article
Engineering, Electrical & Electronic
Chu-Ying Tang, Hong-Hao Lu, Ze-Peng Qiao, Yang Jiang, Fang-Zhou Du, Jia-Qi He, Yu-Long Jiang, Qing Wang, Hong-Yu Yu
Summary: A robust ohmic contact process with ultralow contact resistivity on p-GaN/AlGaN/GaN is demonstrated, and a new contact formation mechanism is proposed.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Sai Pan, Youming Lu, Zhibin Liang, Chaojun Xu, Danfeng Pan, Yugang Zhou, Rong Zhang, Youdou Zheng
Summary: The study investigated the electrical and optical properties of Ag/p-GaN contacts, finding that the presence of oxygen improves the formation of ohmic contacts and promotes the formation of an Ag-Ga solid solution. Based on the results, optimal annealing conditions for blue and green LEDs were suggested.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Physics, Applied
Kazuki Ohnishi, Naoki Fujimoto, Shugo Nitta, Hirotaka Watanabe, Shun Lu, Manato Deki, Yoshio Honda, Hiroshi Amano
Summary: This study demonstrates the precise control of Mg concentration in p-type GaN layers using the halide vapor phase epitaxy method. By adjusting the input partial pressure of MgCl2, the Mg concentration in GaN layers can be effectively controlled. The samples exhibit high structural qualities and the acceptor concentration is in good agreement with the concentration of Mg, suggesting that almost all Mg atoms act as acceptors.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Taoufik Slimani Tlemcani, Clement Mauduit, Micka Bah, Meiling Zhang, Matthew Charles, Romain Gwoziecki, Arnaud Yvon, Daniel Alquier
Summary: This study investigates the formation of Au-free Ohmic contacts on p-type GaN using a bilayer Ni/Al-doped ZnO (AZO) thin film. The results show that the contact resistance can be significantly reduced using a suitable thermal process, reaching the lowest value of 1.85 x 10-4 ohm·cm2 for a sample with a 5 nm Ni layer annealed at 500 degrees C in air for 5 min.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Computer Science, Information Systems
Pengfei Li, Shuhua Wei, Xuanwu Kang, Yingkui Zheng, Jing Zhang, Hao Wu, Ke Wei, Jiang Yan, Xinyu Liu
Summary: The study developed an oxygen plasma surface treatment to reduce the ohmic contact resistance for AlGaN/GaN HEMTs on a high-resistive Si substrate. By optimizing the oxygen plasma conditions, a lower resistance was obtained, with the primary factor being the large nitrogen vacancy induced by the oxygen plasma treatment.
Article
Physics, Condensed Matter
Haiyong Wang, Wei Mao, Shenglei Zhao, Jiabo Chen, Ming Du, Xuefeng Zheng, Chong Wang, Chunfu Zhang, Jincheng Zhang, Yue Hao
Summary: The p-GaN RB-HEMT, featuring a p-GaN layer embedded in the ohmic drain, achieves reverse blocking capability and effectively suppresses reverse leakage current, leading to ultralow reverse leakage current and high reverse breakdown voltage. Moreover, the device exhibits a positive threshold voltage, forward breakdown voltage, and linear relationship between Von, Ron, and p-GaN drain dimension.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Fan Zhang, Rong Xin Wang, Aiqin Tian, Fangzhi Li, Jianping Liu, Hui Yang
Summary: Deposition of Pd/Pt/Au three-layer films on p-GaN under high and ultra-high vacuum conditions was studied to investigate the electrical contact properties. Linear I-V curves were observed in samples deposited under ultra-high vacuum conditions, while nonlinear I-V characteristics were obtained in samples deposited under high vacuum conditions. The study also found that the samples deposited under high vacuum conditions had higher amounts of oxygen and Pd oxide. The oxide layer had an additional influence on the electrical characteristics of the Pd/Pt/Au/p-GaN contact.
Article
Chemistry, Physical
Fei Cao, Yang-xi Xu, Jin-chi Sui, Xing-ji Li, Jian-qun Yang, Ying Wang
Summary: This paper investigates the electrical and structural properties of Cu/Ti/Al ohmic contacts to p-type 4H-SiC with different annealing temperatures and Cu layer thicknesses. The results show that the Cu/Ti/Al contact forms ohmic contact with a contact resistivity of 1.0×10-4 Ω·cm2 after annealing at 800 degrees C. The surface roughness and number of pits on the sample surface increase with the increase of annealing temperature.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Energy & Fuels
Alessandro Borghese, Alessandro Di Costanzo, Michele Riccio, Luca Maresca, Giovanni Breglio, Andrea Irace
Summary: This work presents a comparison of gate-driving requirements for p-GaN HEMTs with Schottky and Ohmic gate contacts, and experimentally verifies the presence of gate current in both device types. It proposes using gate current as a temperature-sensitive parameter and examines the feasibility of monitoring gate current during real circuit operation without adding complexity to the gate driver, through experimental measurements on commercially available p-GaN HEMTs.
Article
Engineering, Electrical & Electronic
Vanjari Sai Charan, Sandeep Vura, R. Muralidharan, Srinivasan Raghavan, Digbijoy N. Nath
Summary: A novel Sc/Al/Ni/Au metal scheme was developed for Ohmic contacts to InAIN/GaN HEMT structures on silicon, achieving a contact resistance of 0.39 Omega-mm and low surface roughness after annealing. Microstructural analysis revealed the formation of ScGaN inclusions in the GaN channel layer and a non-uniform layer of ScInAIN on top of the InAIN barrier, with field-emission as the dominant conduction mechanism. Polarization mismatch due to structural modifications was suggested as the possible mechanism related to Ohmic contact formation.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Clement Mauduit, Taoufik Slimani Tlemcani, Meiling Zhang, Arnaud Yvon, Nicolas Vivet, Matthew Charles, Romain Gwoziecki, Daniel Alquier
Summary: In this study, the importance of layer distribution after annealing to form a high quality ohmic contact on p-type GaN was investigated using nickel (Ni) and gold (Au) thin layer association. The Au/Ni stack showed the most promising results.
MICROELECTRONIC ENGINEERING
(2023)