Article
Optics
Lei Han, Yuanbin Gao, Sheng Hang, Chunshuang Chu, Yonghui Zhang, Quan Zheng, Qing Li, Zi-Hui Zhan
Summary: This work proposes GaN-based VCSELs with the p-AlGaN/p-GaN structure to enhance the laser power. The p-AlGaN/p-GaN heterojunction can store electric field and adjust the drift velocity and kinetic energy of holes, improving the thermionic emission process. Additionally, by using the p-AlGaN layer, the valence band barrier height in the p-EBL can be reduced, leading to better stimulated radiative recombination rate and increased laser power.
CHINESE OPTICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Soungmin Bae, Yoon-Gu Kang, Kodai Ichihashi, Mohammad Khazaei, Varghese Swamy, Myung Joon Han, Kee Joo Chang, Ken-ichi Shudo, Hannes Raebiger
Summary: This study suggests that strain engineering can release trapped hole carriers in gallium nitride materials, solving the challenge of p-type doping. Additionally, the photoluminescence spectrum of magnesium impurities can be tuned by lattice strain, allowing for efficient control of gallium nitride light emission.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Physics, Applied
Liwen Cheng, Jiayi Zhang, Jundi Wang, Jun Zhang, Jinpeng Yang, Shudong Wu, Qinyu Qian, Haitao Chen
Summary: The study suggests that the InGaN laser diode with InGaN-GaN-InGaN quantum barriers outperforms the conventional GaN and InGaN quantum barriers due to properly adjusted refraction index profile and energy band diagrams. The optimized design leads to suppressed leakage of the optical field and electrons, and enhanced injection of holes into the active region.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Optics
Zhongming Zheng, Yukun Wang, Yang Mei, Hao Long, Leiying Ying, Zhiwei Zheng, Baoping Zhang
Summary: This study proposes a new periodic structure to replace the ITO current spreading layer in GaN-based VCSELs, aiming to lower the threshold and increase the laser power.
Article
Optics
H. Zi, W. Y. Fu, F. Tabataba-Vakili, H. Kim-Chauveau, E. Frayssinet, P. De Mierry, B. Damilano, J-Y Duboz, Ph Boucaud, F. Semond, H. W. Choi
Summary: Microdisks fabricated with III-nitride materials grown on GaN substrates demonstrate high material quality of homoepitaxial films and advanced micro-fabrication processes. The microdisks achieve an internal quantum efficiency of around 40% and exhibit low threshold optically pumped lasing at the dominant lasing wavelength.
Article
Crystallography
Zhenyu Chen, Feng Liang, Degang Zhao, Jing Yang, Ping Chen, Desheng Jiang
Summary: The surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied under different flow rates of ammonia during MOCVD growth to explore the optimal growth conditions for green laser diodes. Temperature-dependent photoluminescence (TDPL) examination revealed different emission peak characteristics, indicating significant structural changes in InGaN layers and the presence of composite structures of InGaN/GaN quantum wells and quantum-dot-like centers. It was found that these changes were caused by effects induced by ammonia, including promotion of indium incorporation, corrosion from hydrogen, and reduction in the surface energy of InGaN dot-like centers. Detailed research was conducted to determine ammonia's mechanism of action during InGaN layer growth.
Article
Engineering, Electrical & Electronic
Wei Ou, Yang Mei, Daisuke Iida, Huan Xu, Minchao Xie, Yiwei Wang, Lei-Ying Ying, Bao-Ping Zhang, Kazuhiro Ohkawa
Summary: In this study, InGaN-based orange-red RCLEDs were successfully fabricated using a unique structure and technique, achieving low optical loss in the resonant cavity. The performance of the devices was validated through far-field emission observation and simulation, demonstrating the consistency between performance and design. This research is of significance for the development of displays and communication systems.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Physics, Applied
Boyang Lu, Zhibiao Hao, Yi Luo, Changzheng Sun, Yanjun Han, Bing Xiong, Jian Wang, Hongtao Li, Lai Wang
Summary: This study discusses the behavior of photogenerated carriers in InGaN/GaN LEDs and reveals the shared transport channel between carrier escape and injection processes. Experimental results further confirm this finding by comparing forward voltage and open-circuit voltage. These results are of great significance for enhancing our understanding of device physics and guiding device design.
APPLIED PHYSICS EXPRESS
(2022)
Article
Engineering, Electrical & Electronic
Feifan Xu, Guobin Wang, Tao Tao, Zhe Zhuang, Qi-Ang Yan, Ting Zhi, Zili Xie, Bin Liu, Wengang Bi, Ke Xu, Rong Zhang
Summary: As state-of-the-art displays advance, micro light-emitting diodes (Micro-LEDs) are emerging as a pivotal player due to their small pixel size and efficiency. By investigating Micro-LEDs with different quantum structures, we have shown significant improvement in optoelectronic properties at low current injection. Thinning the InGaN quantum well enhances the electron-hole wave function overlap, increasing radiation efficiency, while a thinner GaN barrier achieves uniform carrier distribution and reduced quantum confinement stark effect (QCSE) in multiple quantum wells (MQWs). Optimized Micro-LEDs exhibit uniform emission and high brightness, making them suitable for full-color displays when combined with quantum dots (QDs).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Optics
Dario Schiavon, Mikolaj Chlipala, Piotr Perlin
Summary: In nitride semiconductors, LED efficiency is limited by the ability of holes to populate only the topmost quantum wells. Using lateral carrier injection design can help alleviate this issue and improve energy efficiency in the structure.
Article
Chemistry, Analytical
Yu-Hsun Huang, Zi-Xian Yang, Su-Ling Cheng, Chien-Hung Lin, Gray Lin, Kien-Wen Sun, Chien-Ping Lee
Summary: The performance of PC surface-emitting lasers with double-hole structure was studied, and it was found that there is a mode switching in threshold mode when the double-hole shift exceeds a certain level. The experimental results showed that modal gain discrimination is dominated by mode wavelength separation.
Article
Materials Science, Multidisciplinary
Natalia Fiuczek, Marta Sawicka, Anna Feduniewicz-Zmuda, Marcin Siekacz, Mikolaj Zak, Krzesimir Nowakowski-Szkudlarek, Grzegorz Muziol, Pawel Wolny, John J. Kelly, Czeslaw Skierbiszewski
Summary: This study demonstrates the electrochemical etching (ECE) of p-type GaN under constant bias without an external light source for the first time. By using a tunnel junction (TJ) as a cap, stable and controllable hole injection to the p-type semiconductor is achieved. The results provide a method for controllable ECE of p-type GaN using TJ for efficient hole injection.
Article
Optics
Mirsaeid Sarollahi, Pijush K. Ghosh, Manal A. Aldawsari, Shiva Davari, Malak Refaei, Reem Alhelais, Yuriy Mazur, Morgan E. Ware
Summary: Graded InGaN structures were designed by increasing indium composition, forming a Zig-Zag quantum well with broadband emission shifting to lower energies. The lowest energy band-to-band transition shifts noticeably with higher indium content, making the structure useful in optoelectronic devices.
JOURNAL OF LUMINESCENCE
(2021)
Article
Engineering, Electrical & Electronic
Ying Ke, Cheng-Jie Wang, Guo-Yi Shiu, Yi-Yun Chen, Yung-Sen Lin, Hsiang Chen, Jung Han, Chia-Feng Lin
Summary: In this study, InGaN VCSELs with top dielectric and bottom pipe-GaN DBRs were demonstrated. The optical birefringence behavior of the pipe-GaN structure induced polarization properties in reflectance and EL spectra, resulting in high polarization ratios of the EL emission peaks.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Materials Science, Multidisciplinary
Wei-Lin Huang, Ming-Chen Tsai, Ting-Heng Wang, Sheng-Yuan Chu, Po-Ching Kao
Summary: In this study, a novel hole injection layer with gradually-doped tripe-layer structure (HITL) was fabricated by using Nb-doped ZnO (NZO) and N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) in organic light-emitting diodes (OLED). The HITL structure effectively improved the current efficiency of the OLED device, and the highest occupied molecular orbital (HOMO) energy level played a key role in enhancing the hole injection performance. The non-destructive analysis method of capacitance-voltage revealed the movement of charge carriers during device operation. The study demonstrated that the stepwise doped double-layer injection layer showed better carrier injection performance with a smaller doping gradient.
ORGANIC ELECTRONICS
(2022)
Article
Physics, Applied
Fuping Huang, Chunshuang Chu, Xingyu Jia, Kangkai Tian, Yonghui Zhang, Quan Zheng, Qing Li, Zi-Hui Zhang
Summary: A hybrid trench MOS barrier Schottky diode (TMBS) structure is proposed to improve the forward current density and the breakdown voltage. By combining the conventional TMBS rectifier with a p-NiO/n-GaN diode, the embedded p-type NiO layer forms a PN junction and improves the current density and breakdown voltage.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Optics
Jiamang Che, Hua Shao, Chunshuang Chu, Qingqing Li, Yonghui Zhang, Xiaowei Sun, Zi-Hui Zhang
Summary: In this study, a 280-nm-wavelength deep-ultraviolet light-emitting diode (DUV LED) with an improved structure and material combination was fabricated and investigated. The device showed enhanced efficiency and improved current spreading effect, while reducing energy loss and leakage current.
Article
Physics, Applied
Fuping Huang, Chunshuang Chu, Zhizhong Wang, Yonghui Zhang, Jiandong Ye, Yuanjie Lv, Hehe Gong, Yongjian Li, Zi-Hui Zhang, Shulin Gu, Rong Zhang
Summary: In this study, we report a GaN-based Schottky barrier diode with improved performance achieved by implementing a p-NiO field ring and field plate. The device demonstrates low turn-on voltage, low on-resistance, nearly unity ideality factor, and high on/off current ratio. Furthermore, the breakdown voltage is significantly increased, resulting in a high Baliga's power figure-of-merit.
APPLIED PHYSICS EXPRESS
(2022)
Article
Optics
Qingqing Li, Chunshuang Chu, Weidong Wang, Jiamang Che, Hua Shao, Qianqian Liu, Yonghui Zhang, Zi-Hui Zhang
Summary: This report presents the design of a p(+)-GaN/SiO2/Ni tunnel junction with a local SiO2 insulation layer for commercially structured AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) with a thin p-GaN layer. The results show that the local SiO2 layer creates an in-plane unbalanced energy band in the p-GaN layer, enhancing the carrier transport paths and increasing the spread of holes, leading to improved optical power compared to conventional DUV LEDs. The study also investigates the influence of the position of the SiO2 insulation layer on the current distribution, finding that placing it in the middle position of the p(+)-GaN layer increases the hole injection efficiency for commercially structured DUV LEDs.
Article
Nanoscience & Nanotechnology
Tong Wei, Kai Lian, Jiaqi Tao, Hu Zhang, Da Xu, Jiachen Han, Chao Fan, Zihui Zhang, Wengang Bi, Chun Sun
Summary: A large-area liquid luminescent solar concentrator (LSC) with high photoluminescence quantum yield (PLQY) and optical conversion efficiency has been fabricated using Mn-doped perovskite materials.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Yongfei Chen, Jiamang Che, Chunshuang Chu, Hua Shao, Yonghui Zhang, Zi-Hui Zhang
Summary: In this study, we improve the current spreading effect and enhance the external quantum efficiency of AlGaN-based DUV LEDs by sandwiching a p-AlGaN layer into the n-AlGaN layer, which generates an energy barrier. The more homogenized current distribution achieved reduces the forward voltage and suppresses the self-heating effect.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Fuping Huang, Zhizhong Wang, Chunshuang Chu, Qianqian Liu, Yongjian Li, Zhen Xin, Yonghui Zhang, Qian Sun, Zi-Hui Zhang
Summary: In this study, we conducted systematic studies on the interfacial conditions for Gallium Nitride-based trench Metal/Insulator/Semiconductor (MIS) type Barrier Schottky Rectifier using T-CAD tool. Our findings suggest that donor-type traps reduce the Schottky barrier height, resulting in increased leakage current and reduced breakdown voltage. On the other hand, acceptor-type traps at the contact interface and mesa sidewall increase the barrier height and turn-on voltage. We propose using an MIS structure with a 1-nm Al2O3 insulation layer to solve the complicated interfacial conditions and reduce reverse leakage significantly.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Optics
Sheng Hang, Gai Zhang, Chunshuang Chu, Yonghui Zhang, Quan Zheng, Qing Li, Zi-Hui Zhang
Summary: This report systematically investigates the impact of different mesa designs on the optical and electrical characteristics of GaN-based micro-LEDs. The results show that using beveled mesas can enhance light extraction efficiency, but it also increases charge-coupling effect and nonradiative recombination.
Article
Engineering, Electrical & Electronic
Zupin Liu, Chunshuang Chu, Bingxiang Wang, Guansen Huang, Ke Jiang, Yonghui Zhang, Xiaojuan Sun, Zi-Hui Zhang, Dabing Li
Summary: In this work, a metal/Ga2O3/AlGaN/GaN hybrid-structured metal-semiconductor-metal ultraviolet photodetector (MSM UV PD) with low dark current has been proposed and fabricated. The device exhibits low dark current due to the depletion region formed by the metal gate and the AlGaN layer. In the illumination condition, photogenerated electrons are efficiently collected by the device, resulting in a high photo-to-dark current ratio and detectivity.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Yuanbin Gao, Chunshuang Chu, Sheng Hang, Yonghui Zhang, Jianwei Zhou, Zi-Hui Zhang
Summary: In this study, we propose increasing the output power of GaN-based VCSELs by engineering the anti-phase surface relief structure and current aperture size. The anti-phase surface relief structure helps achieve Gaussian-shaped near-field and far-field patterns for VCSELs. However, it leads to mirror loss and decreased laser power, which can be mitigated by reducing the current injection aperture size.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Optics
Kaijie Ji, Kaikang Tian, Yuanbin Gao, Sheng Hang, Chunshuang Chu, Yonghui Zhang, Zi-Hui Zhang
Summary: In this paper, the impact of AlN/GaN distributed Bragg reflector (DBR) and AlInN/GaN DBR on stimulated radiative recombination for GaN-based vertical-cavitysurface-emitting lasers (VCSELs) was investigated using advanced numerical models. It was found that the VCSEL with AlInN/GaN DBR decreases the polarization-induced electric field in the active region, increasing electron-hole radiative recombination. However, the AlInN/GaN DBR has reduced reflectivity compared to the AlN/GaN DBR. The paper suggests the use of more pairs of AlInN/GaN DBR to further increase laser power.
Article
Automation & Control Systems
Jianlong Kang, Qing Liu, Haoze Luo, Hu Cao, Zi-Hui Zhang, Zhen Xin
Summary: Investigating the degradation mechanism of silicon carbide (SiC) MOSFETs during short-circuit (SC) is crucial for improving the overall reliability of power converters. While previous research has mainly focused on the on-state phase of SC, this article comprehensively investigates the degradation mechanism of SiC MOSFETs in the off-state phase of short-circuit tests (SCTs). Using technology computer-aided design (TCAD) simulation, the distribution and magnitude of electrothermal stress on the devices under test in the off-state phase of SCTs are analyzed, revealing important phenomena such as long-term high temperature and high electric field stress when applying negative turn-off gate voltage (Vgs-off). Experimental results confirm the observed degradation in the off-state phase and highlight the impact of excessively low Vgs-off on the SC capability of SiC MOSFETs. The degradation mechanism of SiC MOSFETs' static parameters is also analyzed in detail.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Zhan Xuan, Chunshuang Chu, Kangkai Tian, Zhengji Zhu, Zhiwei Xie, Ke Jiang, Yonghui Zhang, Xiaojuan Sun, Zi-Hui Zhang, Dabing Li
Summary: In this report, a polarization-doped n-p-i-p-n GaN/AlxGa1-xN/GaN ultraviolet phototransistor with an Al0.20Ga0.80N insertion layer is proposed. The device shows a low dark current and a high photo-to-dark-current ratio, with fast response time and reduced electron leakage.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Applied
Zhizhong Wang, Fuping Huang, Chunshuang Chu, Yonghui Zhang, Qian Sun, Zi-Hui Zhang
Summary: Using numerical TCAD simulations, we studied the impact of different field plates on the electrical characteristics of lateral AlGaN/GaN-based SBDs with recessed anode. The proposed SBDs with a field plate can generate charge-coupling effect, reducing the electric field at the metal/sidewall interface. The electric field profiles can be influenced by the length of the field plate, insulation layer thickness, and different insulation materials.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Optics
Tong Jia, Muyao Zhang, Gai Zhang, Sheng Hang, Chunshuang Chu, Yonghui Zhang, Zi-Hui Zhang
Summary: This work systematically studies the effect of conventional nano-patterned sapphire substrate (NPSS) on the optical crosstalk and light extraction efficiency (LEE) for InGaN/GaN-based flip-chip micro light-emitting diodes (mu-LEDs) using the 3D FDTD method. The conventional NPSS is found to be unsuitable for mu-LEDs due to the introduction of guided light and poor scattering effect. To improve the optical crosstalk, an air layer or air-cavity patterned sapphire substrate (AC-PSS) can be used as a light filter. The AC-PSS shows promising results in reducing crosstalk ratio and enhancing LEE.
