Ultrahigh-Performance Photovoltaic Ga<sub>2</sub>O<sub>3</sub> Solar-Blind Ultraviolet Detectors via Two-Dimensional Step-Flow Growth and Drift Region Optimization
Shoudong Zhu, Zhenjie Zheng, Yaoping Lu, Hao Long, Jiachang Zhuang, Lemin Jia, Duanyang Chen, Titao Li, Hongji Qi, Wenbi Cai, Xiang Cheng, Xiaorui Xu, Min Zhu, Haizhong Zhang, Xiaoqiang Lu
Abstract
Photovoltaic solar-blind ultraviolet photodetectors (SBPDs) operate independently of an external power source, addressing critical demands in extreme environments, such as forest fire detection and atmospheric ozone layer monitoring. Gallium oxide (Ga 2 O 3 ) offers significant potential for extreme applications due to its radiation resistance and high-temperature stability. Here, we present a novel homoepitaxy strategy to produce an “atomic smooth” step-flow Ga 2 O 3 photosensitive layer, successfully fabricating device-grade Ga 2 O 3 /n + -Ga 2 O 3 homojunctions for photovoltaic SBPDs. These devices exhibit a maximum open-circuit voltage of 1.0 V, an ultrahigh external quantum efficiency of 59.5%, and an ultrafast response time of 100 ns under zero bias, maintaining consistent performance even at 390 K. By implementing a 2D step-flow growth mode, both bulk and interface defects were effectively suppressed, achieving the desired band alignment. Furthermore, the optimized high-quality depletion region formed by the Ga 2 O 3 layer facilitates enhanced carrier drift, resulting in an efficient carrier collection. This work fully explores the potential of Ga 2 O 3 SBPDs for extreme applications and provides an effective design strategy for achieving photovoltaic detectors characterized by zero power consumption, high responsivity, and rapid response.