Article
Engineering, Electrical & Electronic
Houqiang Fu, Kai Fu, Srabanti Chowdhury, Tomas Palacios, Yuji Zhao
Summary: This comprehensive review discusses the recent progress in vertical GaN power devices, focusing on device design principles and fabrication processes. It covers basic structures, fabrication processes, and device physics, including materials and device engineering aspects. Key topics such as avalanche breakdown and leakage mechanisms are also discussed, providing valuable information for researchers and inspiring future interdisciplinary collaborations.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Xiaolu Guo, Yaozong Zhong, Yu Zhou, Xin Chen, Shumeng Yan, Jianxun Liu, Xiujian Sun, Qian Sun, Hui Yang
Summary: This work presents a 1200-V quasi-vertical GaN-on-Si p-n diode with a 6.6-μm thick high-quality GaN drift layer, which exhibits excellent static and dynamic performance. The diode shows stable operation at high temperatures and can effectively recover after power cycling tests. The experimental results indicate a reduced dependence of the dynamic on-resistance on the off-state voltage.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Houqiang Fu, Kai Fu, Srabanti Chowdhury, Tomas Palacios, Yuji Zhao
Summary: The article discusses the design principles, physics, and advanced power rectifiers of vertical gallium nitride (GaN) power devices, as well as the related key fabrication processes and performance metrics analysis. Additionally, it mentions the progress made in critical processes such as selective area doping and regrowth in the fabrication of vertical GaN power devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Chen Yang, Houqiang Fu, Kai Fu, Tsung-Han Yang, Jingan Zhou, Jossue Montes, Yuji Zhao
Summary: This paper investigates low-leakage hydrogen plasma (HP) terminated GaN-on-GaN vertical p-n diodes, achieving significant reductions in leakage current and improvements in breakdown voltage with a p-GaN extension design. The devices demonstrate non-destructive breakdown voltage of 1.68 kV, specific on-resistance of 0.40 MΩcm², and Baliga's figure of merit of 7.1 GWcm(-2), showing the effectiveness of HP termination with p-GaN extension in enhancing the performance of vertical GaN power diodes.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Yuan Qin, Ming Xiao, Ruizhe Zhang, Qingyun Xie, Tomas Palacios, Boyan Wang, Yunwei Ma, Ivan Kravchenko, Dayrl P. Briggs, Dale K. Hensley, Bernadeta R. Srijanto, Yuhao Zhang
Summary: This work presents the fabrication of quasi-vertical GaN Schottky barrier diodes (SBDs) on a 6-inch Si substrate with a record-breaking breakdown voltage (BV) of over 1 kV. The novel use of a deep mesa in quasi-vertical devices allows for a self-aligned edge termination, and the mesa sidewall is covered by p-type nickel oxide (NiO) to reduce the surface field. The device exhibits a parallel-plane junction electric field of 2.8 MV/cm, along with low turn-on voltage and specific on-resistance. Additionally, it demonstrates excellent overvoltage robustness under continuous stress.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Nilushi Wijeyasinghe, Olga Solomeshch, Nir Tessler, Dimitra G. Georgiadou, Thomas D. Anthopoulos
Summary: This study reports on CuSCN Schottky diodes that are processed from solution with nanogap electrodes and doped with C60F48 to improve their operating characteristics. The doped diodes exhibit enhanced performance and are suitable for flexible circuits and IoT devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Analytical
Kalparupa Mukherjee, Carlo De Santi, Matteo Buffolo, Matteo Borga, Shuzhen You, Karen Geens, Benoit Bakeroot, Stefaan Decoutere, Andrea Gerosa, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This study investigates the breakdown characteristics and leakage processes of p(+)n(-)n GaN-on-Si vertical structures through experiments and simulations, identifying the impact of different p-doping concentrations on the design of breakdown voltage.
Review
Chemistry, Physical
Yu Zhang, Chao Liu, Min Zhu, Yuliang Zhang, Xinbo Zou
Summary: This article presents a review of recent progress in GaN two-terminal devices grown on lattice-mismatched Si substrates. Advances in material epitaxy, device design, and fabrication technology for GaN diodes are illustrated, along with a comprehensive overview of static and dynamic characteristics for p-i-n diodes. The achievements in cracks-free LED-on-Si and micro-LED display using GaN-on-Si epitaxy are discussed, highlighting the great potential of GaN-based device technology.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Optics
Qifeng Lyu, Huaxing Jiang, Kei May Lau
Summary: The study demonstrates the first integration of monolithically integrated UV LEDs and visible-blind UV PDs on Si substrate, achieving high sensitivity and low dark current. By optimizing the structure and materials, it offers potential for various applications with high-performance UV PDs and LEDs.
Article
Engineering, Electrical & Electronic
Xuan Liu, Maojun Wang, Jin Wei, Cheng P. Wen, Bing Xie, Yilong Hao, Xuelin Yang, Bo Shen
Summary: Utilizing hydrogen plasma treatment and controlled diffusion, a junction termination extension (JTE) structure with gradient hole density (GHD) is spontaneously formed for vertical gallium nitride (GaN) p-n diode based on selective area partial passivation of Mg acceptors with hydrogen. The reverse bias for the quasi-vertical GaN-on-Si p-n diodes to reach a leakage current of 1 A/cm(2) was boosted from 631 to 1100 V. Additionally, the fabricated diode exhibited superior rectifying behavior with an ON/OFF-current ratio of 10(12) and a specific differential ON-resistance of 0.75 m omega middot cm(2).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Jingcun Liu, Ruizhe Zhang, Ming Xiao, Subhash Pidaparthi, Hao Cui, Andrew Edwards, Lek Baubutr, Cliff Drowley, Yuhao Zhang
Summary: This letter presents the avalanche and surge current ruggedness of the industry's first 1.2-kV-class vertical GaN p-n diodes on 100-mm GaN substrates. The diodes exhibit a critical avalanche energy density and surge energy density, as well as small reverse recovery and fast switching capabilities, highlighting the high ruggedness of GaN p-n junctions.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Physics, Applied
Kai Fu, Houqiang Fu, Xuguang Deng, Po-Yi Su, Hanxiao Liu, Kevin Hatch, Chi-Yin Cheng, Daniel Messina, Reza Vatan Meidanshahi, Prudhvi Peri, Chen Yang, Tsung-Han Yang, Jossue Montes, Jingan Zhou, Xin Qi, Stephen M. Goodnick, Fernando A. Ponce, David J. Smith, Robert Nemanich, Yuji Zhao
Summary: The paper investigates the silicon (Si) contamination issue in gallium nitride (GaN) power devices and presents an approach to reduce its impact on device performance. Through optimized etching methods and chemical treatment, the silicon concentration levels at the regrowth interface can be effectively lowered, leading to improved performance in vertical GaN-based p-n diodes.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Shuzhen You, Karen Geens, Matteo Borga, Hu Liang, Herwig Hahn, Dirk Fahle, Michael Heuken, Kalparupa Mukherjee, Carlo De Santi, Matteo Meneghini, Enrico Zanoni, Martin Berg, Peter Ramvall, Ashutosh Kumar, Mikael T. Bjork, B. Jonas Ohlsson, Stefaan Decoutere
Summary: This paper reviews recent progress and key challenges in process and reliability for high-performance vertical GaN transistors and diodes, with a focus on 200 mm CMOS-compatible technology. It demonstrates the potential of using 200 mm diameter CTE matched substrates for vertical power transistors, and gate module optimizations for device robustness. An alternative technology path based on coalescence epitaxy GaN-on-Silicon is introduced, which could enable thick drift layers of very low dislocation density.
MICROELECTRONICS RELIABILITY
(2021)
Article
Engineering, Electrical & Electronic
Georgios Doundoulakis, Dimitris Pavlidis
Summary: The electrical characteristics of simulated vertical gallium nitride nanowire vacuum field emission diodes and transistors were investigated, showing changes in turn-on voltage, saturation emitter current density, and transfer characteristics depending on geometry and material parameters. Sharp-tip GaN nanowires demonstrated decreased turn-on voltage and increased saturation emitter current density, while sharp-tip VFETs displayed reduced threshold voltage, increased transconductance, and improved ON-/OFF-current ratio compared to flat-tip ones. The output characteristics of both types of devices exhibited nonlinear behavior at low voltage regimes.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Review
Chemistry, Analytical
Catherine Langpoklakpam, An-Chen Liu, Yi-Kai Hsiao, Chun-Hsiung Lin, Hao-Chung Kuo
Summary: This review provides a concise overview of the significance and unique architecture of vertical GaN MOSFETs, discusses their advantages and recent advancements, and suggests methods to enhance their breakdown voltage.
Article
Engineering, Electrical & Electronic
Paiwen Fang, Chang Rao, Chao Liao, Shujian Chen, Zhisheng Wu, Xing Lu, Zimin Chen, Gang Wang, Jun Liang, Yanli Pei
Summary: This study reports the effects of O-2 or N-2 microwave plasma treatment on beta-Ga2O3 surface prior to Schottky metal deposition. The device uniformity of Schottky barrier diodes is significantly improved by the microwave plasma treatments without any degradation. The relatively low Schottky barrier height with O-2 microwave plasma treatment corresponds to high reverse leakage current.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2022)
Article
Optics
Longheng Qi, Xu Zhang, Wing Cheung Chong, Kei May Lau
Summary: This paper demonstrates a monolithic full-color micro-LED microdisplay with a resolution of 423 pixels per inch by integrating a blue GaN-on-Si display module and a quantum dots photoresist color conversion module. The result is a full-color micro-LED display with a wide color gamut and high brightness. The prototype shows potential scalability and low-cost volume production of high-resolution full-color micro-LED microdisplays.
PHOTONICS RESEARCH
(2023)
Article
Engineering, Electrical & Electronic
Jing Wang, Leidang Zhou, Xing Lu, Liang Chen, Zimin Chen, Xinbo Zou, Gang Wang, Boming Yang, Xiaoping Ouyang
Summary: In this study, ultrafast X-ray detectors were fabricated using a high resistivity unintentionally-doped epsilon-Ga2O3 film grown on sapphire by metal-organic chemical vapor deposition (MOCVD). The detector exhibited low dark current and high sensitivity, with stable and repeatable transient response under switching X-ray illumination. Furthermore, the detector achieved pulsed X-ray detection with a narrow time resolution. These results demonstrate the great potential of MOCVD-grown high-resistivity epsilon-Ga2O3 film for ultrafast X-ray detection.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Luyu Wang, Zhiyang Xie, Beibei Pan, Zhiqi Zhou, Linze Li, Xinbo Zou, Haiming Ji, Baile Chen
Summary: We present a novel 850 nm high-speed photodetector that can simultaneously achieve high-speed data acquisition and electrical power generation. It is based on a GaAs/AlGaAs modified uni-traveling carrier photodetector (MUTC-PD). Compared to traditional p-i-n photodetectors with the same absorber thickness, the MUTC device exhibits a high 3 dB bandwidth of 11.9 GHz and a power conversion efficiency of 38.5% under a forward bias of +0.7 V. This exceptional performance is achieved by incorporating the MUTC structure on LPC devices. The device is expected to find applications in simultaneous lightwave information and power transfer, offering a potential solution for next-generation combined power and data transceiver modules.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Chemistry, Physical
Yuxin Deng, Ziqi Yang, Tongling Xu, Huaxing Jiang, Kar Wei Ng, Chao Liao, Danni Su, Yanli Pei, Zimin Chen, Gang Wang, Xing Lu
Summary: Due to the difficulty of p-type doping in beta-Ga2O3, the NiO/beta-Ga2O3 heterojunction is considered as a promising candidate for bipolar devices. In this study, the band alignment and electrical properties of NiO/beta-Ga2O3 heterojunctions with different beta-Ga2O3 orientations were comparatively studied. It was found that there is a type-II band alignment between NiO and beta-Ga2O3, and the valence band offsets and conduction band offsets vary with different substrate orientations. The influence of substrate orientations on the properties of NiO/beta-Ga2O3 heterojunctions is of great importance for the design and optimization of beta-Ga2O3-based heterojunction devices.
APPLIED SURFACE SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Yujia Tu, Weiqu Chen, Zhipeng Zhang, Zimin Chen, Yanli Pei, Gang Wang, Xing Lu
Summary: This letter presents the demonstration of surface acoustic wave (SAW) resonators using a novel epsilon-Ga2O3 piezoelectric semiconductor. A 1-mu m thick phase-pure epsilon-Ga2O3 film was grown on sapphire through metal organic chemical vapor deposition (MOCVD) and fabricated into a single-port SAW resonator with a wavelength of 2.4 mu m. The Rayleigh and Sezawa wave propagation was observed at 1.36 and 2.29 GHz, respectively, through finite element method (FEM) simulation. The study also examined the phase velocities (Vp), electromechanical coupling coefficients (K2), and quality factors (Q) of the fabricated device for both resonate modes.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Applied
Jie Li, Ying Xue, Zhao Yan, Yu Han, Kei May Lau
Summary: To achieve fully integrated silicon photonics, reliable III-V light sources that can efficiently couple with Si/SiN waveguides are crucial. A selective regrowth scheme was developed on a monolithic InP/SOI platform to construct on-chip lasers that can be efficiently coupled with Si/SiN waveguides. Strong photoluminescence emission at the telecom band was obtained on both growth templates, demonstrating the potential for multi-wavelength emission on the same chip. The regrowth method provides a promising solution for the monolithic integration of III-V on-chip lasers on Si.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Optics
Qi Lin, Jie Huang, Liying Lin, Wei Luo, Wen Gu, Kei May Lau
Summary: This article reports on the continuous wave lasing of 980nm electrically pumped quantum well lasers directly grown on silicon, and compares them with lasers grown on other substrates. The results show that although lasers grown on silicon have slightly higher threshold current, it still demonstrates a promising step towards realizing quantum well lasers on silicon.
Article
Optics
Xuetong Zhou, Ying Xue, Fan Ye, Ziyao Feng, Yuan Li, Xiankai Sun, Kei May Lau, Hon Ki Tsang
Summary: We propose and validate a new approach for high coupling efficiency (CE) grating couplers (GCs) in the lithium niobate on insulator photonic integration platform. Enhanced CE is achieved by increasing the grating strength using a high refractive index polysilicon layer on the GC. The optical cavity formed in the vertical direction enhances the CE of the waveguide GC, and simulations predict a CE of -1.40 dB while the experimentally measured CE is -2.20 dB with a 3-dB bandwidth of 81 nm from 1592 nm to 1673 nm. The high CE GC is achieved without using bottom metal reflectors or requiring the etching of the lithium niobate material.
Article
Engineering, Electrical & Electronic
Junmin Jiang, Xu Zhang, Xun Liu, Zhaojun Liu, Liusheng Sun, Shing Hin Yuen, Wing Cheung Chong, Wing-Hung Ki, C. Patrick Yue, Kei May Lau
Summary: This paper demonstrates a fully-integrated active matrix light-emitting diode (AMLED) micro-display system. The system consists of a 36 x 64 AMLED array chip based on GaN-on-Silicon epilayers and a silicon driving chip integrating an on-chip hybrid voltage regulator, pixel drivers, and peripheral circuits. The system achieves high pixel density and can operate directly with a battery without any external passive components.
IEEE JOURNAL ON EMERGING AND SELECTED TOPICS IN CIRCUITS AND SYSTEMS
(2023)
Article
Engineering, Electrical & Electronic
Junmin Zhou, Haowen Guo, Haitao Du, Yu Zhang, Haolan Qu, Wei Huang, Jianjun Zhou, Zhiqiang Xiao, Xinbo Zou
Summary: The low-noise amplification performance of an enhancement-mode p-GaN gate HEMT has been thoroughly investigated in this study, demonstrating its potential for low noise amplifier applications.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Yu Zhang, Yitian Gu, Jiaxiang Chen, Yitai Zhu, Baile Chen, Huaxing Jiang, Kei May Lau, Xinbo Zou
Summary: The OFF-state stress-induced threshold voltage instability and dynamic ON-resistance of GaN MOSHEMT with ZrO2 gate dielectric are investigated. Electron emission at the ZrO2/AlGaN interface is found to cause the threshold voltage shift. The activation energies of emission and capture are extracted by threshold voltage transient spectroscopy. Under OFF-state drain-source bias stressing, the drain current decreases despite the negative shift of threshold voltage, which is related to electron capture in the access region. The results suggest that high-quality ZrO2 is an attractive option for the gate dielectric of GaN MOSHEMTs in power switching electronics.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Optics
Longheng Qi, Peian Li, Xu Zhang, Ka Ming Wong, Kei May Lau
Summary: A prototype of full-color micro-LED micro-display with a pixel density of 391 ppi is demonstrated using InGaN/AlGaInP heterogeneous integration. This display shows the feasibility and prospects of high brightness, good color performance, and high-resolution micro-LED micro-displays in future metaverse applications.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Review
Chemistry, Analytical
Xiazhi Zou, Jiayi Yang, Qifeng Qiao, Xinbo Zou, Jiaxiang Chen, Yang Shi, Kailin Ren, Zeheng Wang, Jing-Kai Huang
Summary: Gallium nitride (GaN) high-electron-mobility transistors (HEMTs) have promising potential for power devices due to their superior advantages, but stability and reliability issues related to traps have limited their development. This article summarizes the locations and energy levels of traps in GaN HEMTs, and reviews the characterization techniques for bulk traps and interface traps.
