Enhancing the light extraction efficiency for AlGaN-based DUV LEDs with a laterally over-etched p-GaN layer at the top of truncated cones.
Enhancing the light extraction efficiency for AlGaN-based DUV LEDs with a laterally over-etched p-GaN layer at the top of truncated cones.
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DOI：
10.1364/oe.435302
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发表时间：
2021-09
期刊：
影响因子：
3.8
通讯作者：
Gai Zhang;Hua Shao;Muyao Zhang;Ziqiang Zhao;Chunshuang Chu;Kangkai Tian;Chao Fan;Yonghui Zhang;Zi-hui Zhang
中科院分区：
文献类型：
--
作者：
Gai Zhang;Hua Shao;Muyao Zhang;Ziqiang Zhao;Chunshuang Chu;Kangkai Tian;Chao Fan;Yonghui Zhang;Zi-hui Zhang
众所周知，采用侧壁倾斜的截锥阵列可以提高AlGaN基深紫外光发射二极管(DUV LED)的光提取效率。在这项工作中，采用空气腔形状的倾斜侧壁，并对截断锥体顶部的p-GaN层进行横向过刻蚀，从而为AlGaN基DUV LED产生更多的光逃逸路径。实验结果表明，与仅具有气腔形倾斜侧壁的DUV LED相比，在不牺牲正向偏置的情况下，在截断锥体顶部横向过刻蚀p-GaN的DUV LED的光功率提高了30%。这是因为过刻蚀的p-GaN对载流子注入几乎没有影响，也不影响欧姆接触电阻。此外，模拟结果表明，由于减小了p-GaN的面积，抑制了光吸收，并为DUV照片提供了额外的光路，因此具有横向过刻蚀p-GaN层的截断锥体可以增强李氏效应。然后，更多的光线将被反射到蓝宝石一侧的逃逸锥体中。
It is known that light extraction efficiency (LEE) for AlGaN-based deep ultraviolet light-emitting didoes (DUV LEDs) can be enhanced by using truncated cone arrays with inclined sidewalls. In this work, the air-cavity-shaped inclined sidewall is applied and the p-GaN layer at the top of the truncated cone is laterally over-etched so that more light escape paths are generated for AlGaN-based DUV LEDs. The experimental results manifest that when compared with DUV LEDs only having the air-cavity-shaped inclined sidewall, the optical power for the DUV LEDs with laterally over-etched p-GaN at the top of the truncated cone is enhanced by 30% without sacrificing the forward bias. It is because the over-etched p-GaN makes little effect on the carrier injection and does not affect the ohmic contact resistance. Moreover, the simulation results show that the truncated cone with laterally over-etched p-GaN layer can enhance the LEE because the reduced p-GaN area can suppress the optical absorption and supplies additional light paths for DUV photos. Then, more light will be reflected into escape cones at the sapphire side.