Promoting Photogenerated Hole Injection into Deep-Ultraviolet LEDs through a Reversed-Biased Selectively-Area-Grown n-GaN/i-GaN/p-GaN PIN Diode
Jianyu Liu, Chong Wang, Kai Guo, Kaixin Li, Xiaona Zhang, Chunshuang Chu, Kangkai Tian, Haoyan Liu, Dongyan Zhang, Yonghui Zhang, Naixin Liu, Jianchang Yan, Zi-Hui ZhangAbstract
This work proposes and demonstrates the integration of reverse-biased selective area growth n-GaN/i-GaN/p-GaN PIN diode into AlGaN-based deep ultraviolet light-emitting diodes (DUV-LEDs) to enhance their wall-plug efficiency (WPE). The PIN photosensitive structure is proposed to absorb trapped photons and convert them into electron−hole pairs through its photoconductive property. The simulation results suggest that the built-in electric field in the PIN junction causes the photogenerated holes to transport into the active region, potentially improving both the light extraction efficiency and the hole injection efficiency. In addition, the exposed p-GaN surfaces between the PIN column arrays facilitate the formation of low-resistance ohmic contacts. Compared with conventional DUV-LEDs, the device integrated with the PIN array achieves a 28.7% improvement in external quantum efficiency (EQE) under an injection current of 350 mA. The forward voltage is reduced from 7.62 V to 7.03 V. As a result, a 39.57% enhancement in WPE is obtained.