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10. Introduction

Author

Zhang, Zi-Hui, Chu, Chunshuang, Tian, Kangkai, Zhang, Yonghui, Zhang, Zi-Hui, Chu, Chunshuang, Tian, Kangkai, and Zhang, Yonghui

Published
2019
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14. Conclusions and Outlook

Author

Zhang, Zi-Hui, Chu, Chunshuang, Tian, Kangkai, Zhang, Yonghui, Zhang, Zi-Hui, Chu, Chunshuang, Tian, Kangkai, and Zhang, Yonghui

Published
2019
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18. 2.5 kV/1.95 GW/cm² AlGaN/GaN-Based Lateral Schottky Barrier Diodes With a High-k Field Plate to Reduce Reverse Current

Author

Wang, Zhizhong, Huang, Fuping, Chu, Chunshuang, Tian, Kangkai, Gong, Hehe, Sun, Na, Zhang, Yonghui, Li, Yongjian, Ye, Jiandong, and Zhang, Zi-Hui

Abstract

In this article, we present AlGaN/GaN-based lateral Schottky barrier diodes (SBDs) on sapphire substrate with fully recessed anodes and $\text{a}\vphantom {_{\int }}$ high-permittivity field plate (FP). A specific ON-resistance of 3.2 $\text{m}\Omega \cdot $ cm2, an on/off current ratio of $10^{{10}}$ , and a reverse breakdown voltage (BV) of 2.5 kV are simultaneously achieved for the device with the anode-to-cathode space of 30 $\mu \text{m}$ . This yields a Baliga’s power figure-of-merit (BFOM) of 1.95 GW/cm2. Our fabricated device shows that the leakage current is hardly affected by the reverse bias. It is because the electric field is pushed apart from the Schottky contact region by the high-permittivity FP. This causes the absence of the defect-related carrier tunneling effect at the Schottky contact region. Meanwhile, the high-permittivity FP helps extend the depletion effect for the drift region and gives rise to the increased BV.

Published
2024
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23. Introduction

Author

Zhang, Zi-Hui, primary, Chu, Chunshuang, additional, Tian, Kangkai, additional, and Zhang, Yonghui, additional

Published
2019
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31. GaN-Based Ultraviolet Phototransistor With Two Parallel Polarization-Doped Junctions and an Al$_{\text{0.20}}$Ga$_{\text{0.80}}$N Insertion Layer to Achieve Low Dark Current and High Detectivity

Author

Xuan, Zhan, primary, Chu, Chunshuang, additional, Tian, Kangkai, additional, Zhu, Zhengji, additional, Xie, Zhiwei, additional, Jiang, Ke, additional, Zhang, Yonghui, additional, Sun, Xiaojuan, additional, Zhang, Zi-Hui, additional, and Li, Dabing, additional

Published
2023
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32. GaN-Based Ultraviolet Phototransistor With Two Parallel Polarization-Doped Junctions and an Al0.20Ga0.80N Insertion Layer to Achieve Low Dark Current and High Detectivity

Author

Xuan, Zhan, Chu, Chunshuang, Tian, Kangkai, Zhu, Zhengji, Xie, Zhiwei, Jiang, Ke, Zhang, Yonghui, Sun, Xiaojuan, Zhang, Zi-Hui, and Li, Dabing

Abstract

In this report, a polarization-doped n-p-i-p-n GaN/AlxGa $_{{1}-{x}}\text{N}$ /GaN ultraviolet phototransistor with an Al0.20Ga0.80N insertion layer is proposed. The AlxGa $_{{1}-{x}}\text{N}$ layer with graded AlN composition is utilized as a p-type layer. The Al0.20Ga0.80N insertion layer is embedded into the unintentionally doped GaN (i-GaN) absorption layer, which can increase the conduction band barrier height and reduce the electron leakage from the substrate for the device. As a result, the dark current lower than $3.40\times 10^{-{11}}$ A/cm2 can be obtained. When the device is illuminated with ultraviolet light, the forward biased junction facilitates the photo-generated carrier transport. As a result, a photo-to-dark-current ratio (PDCR) larger than 104 at the applied bias of 5 V is realized. The carriers are transported in the region far apart from the device surface, and this gives rise a response with the rise time of 27 ms and decay time of 44 ms, respectively.

Published
2023
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36. Understanding omni-directional reflectors and nominating more dielectric materials for deep ultraviolet light-emitting diodes with inclined sidewalls.

Author

Zheng, Yuxin, Zhang, Ji, Chang, Le, Chu, Chunshuang, Tian, Kangkai, Zheng, Quan, Li, Qing, Zhang, Yonghui, Bi, Wengang, and Zhang, Zi-Hui

Subjects
LIGHT emitting diodes, FLIP chip technology, DIELECTRIC materials, FINITE difference time domain method
Abstract

In this work, unique properties and tremendous advantages for an omni-directional reflector (ODR) on an inclined sidewall for flip-chip AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) are systematically investigated via a three-dimensional finite-difference time-domain method. It is found that although the reflectivity of Ag is far lower than that of Al, the light extraction efficiency for the inclined sidewall DUV LED with the Ag-based ODR is not always lower than that with Al-based one within certain incident angles. The reason is that the total internal reflection (TIR) of the ODR on the inclined sidewall plays an important role in extracting light. We also find that the reflectivity for TIR can be strongly suppressed if surface plasmon polaritons (SPPs) resonance absorption occurs. To avoid SPP resonance absorption, our studies in this work propose the design strategy for ODR on the inclined sidewall as follows: if the ODR structure of the DUV LED with an inclined sidewall adopts thin dielectric layers, the high-index material should be selected as the dielectric layer; if a thick dielectric layer is adopted for the ODR structure, the low-index material should be selected as the dielectric layer. [ABSTRACT FROM AUTHOR]

Published
2020
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37. Interplay between various active regions and the interband transition for AlGaN-based deep-ultraviolet light-emitting diodes to enable a reduced TM-polarized emission.

Author

Tian, Kangkai, Chu, Chunshuang, Che, Jiamang, Shao, Hua, Kou, Jianquan, Zhang, Yonghui, Zhou, Xingye, Feng, Zhihong, Wei, Tongbo, and Zhang, Zi-Hui

Subjects
*QUANTUM wells, *DIODES, *QUANTUM efficiency, *STARK effect, *WAVELENGTHS
Abstract

Al-rich AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs) have a low light extraction efficiency, especially when the emission wavelength is shorter than 280 nm, and this is partially because of the dominant transverse-magnetic polarized light. Our results show that the transverse-electric (TE) polarized light can be obtained even if the emission wavelength becomes even shorter by reducing the quantum well thickness. The ultrathin quantum well enables the enhanced TE-polarized emission that arises from the redistributed subbands for holes. On the contrary to the common belief, we observe a blueshift for the emission wavelength when the AlN composition in the quantum barrier increases. The internal quantum efficiency (IQE) for DUV LEDs with ultrathin quantum wells is no longer determined by the quantum-confined Stark effect, while quantum barrier with high AlN composition is vitally important to improve the electron injection efficiency and thus enhance the IQE. [ABSTRACT FROM AUTHOR]

Published
2019
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