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472 results on '"Zhang, Zi-Hui"'

114. On the coupled effect of a MIS-based anode and AlGaN-polarized super-junction to reduce the local electric field for AlGaN/GaN Schottky barrier diodes

Author

He, Jingting, Huang, Fuping, Wang, Zhizhong, Gao, Xuchen, Tian, Kangkai, Zhang, Yonghui, Chu, Chunshuang, Cai, Shuting, Sun, XiaoWei, and Zhang, Zi-Hui

Abstract

This work employs advanced physical models with the help of technology computer-aided design tools to systematically design and investigate AlGaN/GaN Schottky barrier diodes (SBDs), focusing on enhancing forward conduction and reverse blocking characteristics. A recessed metal/insulator/III-nitride (MIS) anode is demonstrated to manage electric field distribution. The incorporation of a 1 nm thick Al2O3layer enables a reduced leakage current and a significant increase in breakdown voltage (BV). Subsequently, tailored field plates (FPs) further improve the BV of the MIS SBD to ∼1650 V but strong electric field magnitude will be found at the edge of the FP. Hence, a MIS SBD with a graded AlGaN barrier layer (MIS-GA SBD) is designed, featuring a gradient decrease in Al content along the [0001] direction. The generation of negative polarization charges within the barrier functions as a super-junction, significantly homogenizing the electric field. As a result, the MIS-GA SBD achieves a remarkable BV exceeding 3500 V, highlighting its strong potential for high-voltage power electronic applications.

Published
2024
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121. MIS-Based GaN Schottky Barrier Diodes: Interfacial Conditions on the Reverse and Forward Properties

Author

Huang, Fuping, Wang, Zhizhong, Chu, Chunshuang, Liu, Qianqian, Li, Yongjian, Xin, Zhen, Zhang, Yonghui, Sun, Qian, and Zhang, Zi-Hui

Abstract

In this work, we have conducted systematic studies on the interfacial conditions for gallium nitride (GaN)-based trench metal/insulator/semiconductor (MIS)-type barrier Schottky rectifier (TMBS) with the help of the T-CAD tools. Our results show that the donor-type traps tend to reduce the Schottky barrier height ( ${q}\varphi _{s}$ ), which weakens the charge coupling effect, increases the leakage current, and finally reduces the breakdown voltage (BV). On the contrary, the acceptor-type traps at the contact interface and mesa sidewall will increase ${q}\varphi _{s}$ and the turn-on voltage ( ${V}_{\mathrm{ON}}$ ) because they can capture electrons in the mesa region and show the negative polarity. This then enhances the electron depletion at the contact interface and the mesa sidewall, resulting in an increase in ${q}\varphi _{s}$ and ${V}_{\mathrm{ON}}$ . Therefore, this process can increase the reverse blocking characteristics. However, for solving the complicated interfacial conditions in the Schottky contact region, we propose using an MIS structure with a 1-nm Al2O3 insulation layer for the GaN-based TMBS rectifiers. Based on the results, the tunneling process and thermionic-emission (TE) process take into account for the current transport mechanism for the MIS-TMBS rectifiers. Meanwhile, the 1-nm thick Al2O3 interlayer increases the effective Schottky barrier height ( ${q}\varphi _{s} + {q}\varphi _{T}$ ), which significantly reduces the reverse leakage. In addition, this design offers more freedom in selecting the Schottky contact electrode for the MIS-TMBS rectifier.

Published
2022
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122. A Buried High k Insulator for Suppressing the Surface Recombination for GaN-Based Micro-Light-Emitting Diodes.

Author

Zhang, Muyao, Hang, Sheng, Chu, Chunshuang, Shao, Hua, Zhang, Yidan, Zhang, Yonghui, Zhang, Yandi, Zheng, Quan, Li, Qing, and Zhang, Zi-Hui

Subjects
SURFACE recombination, DIODES, QUANTUM efficiency, ELECTRIC potential, PERMITTIVITY, FLIP chip technology
Abstract

The external quantum efficiency (EQE) for InGaN/GaN micro-light-emitting diodes ($\mu $ LEDs) is strongly affected by surface recombination at mesa sidewall. In this work, we propose fabricating a Ta2O5 buried insulator in the periphery for the $\mu $ LED mesa to suppress the surface recombination. The Ta2O5 buried insulator with a large relative dielectric constant of 26 can significantly reduce the voltage drop in the insulator so that the lateral energy band below the p-type contact can be bent in the way of generating energy barriers for holes in the mesa edge. This further suppresses the current diffusion to the defected mesa edges for $\mu $ LEDs. Thus, when compared with the reference $\mu $ LED, the proposed $\mu $ LED with $40\times 40\,\,\mu \text{m}^{{2}}$ chip area increases the EQE by 34.6%, and the ON/ OFF current ratio is increased to $10^{{8}}$. A reduced ideality factor of 6.8 is also obtained when compared with other devices. [ABSTRACT FROM AUTHOR]

Published
2022
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129. Polarization-enhanced AlGaN solar-blind ultraviolet detectors

Author

Jiang, Ke, primary, Sun, Xiaojuan, additional, Zhang, Zi-Hui, additional, Ben, Jianwei, additional, Che, Jiamang, additional, Shi, Zhiming, additional, Jia, Yuping, additional, Chen, Yang, additional, Zhang, Shanli, additional, Lv, Wei, additional, and Li, Dabing, additional

Published
2020
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136. Demonstration of ohmic contact using ${{\rm MoO}_{\rm x}}/{\rm Al}$MoOx/Al on p-GaN and the proposal of a reflective electrode for AlGaN-based DUV-LEDs

Author

Li, Liang, primary, Cui, Mei, additional, Shao, Hua, additional, Dai, Yijun, additional, Chen, Li, additional, Zhang, Zi-hui, additional, Hoo, Jason, additional, Guo, Shiping, additional, Lan, Wen’an, additional, Cao, Lili, additional, Xu, Hui, additional, Guo, Wei, additional, and Ye, Jichun, additional

Published
2020
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