Ultrahigh-Performance Photovoltaic Ga2O3 Solar-Blind Ultraviolet Detectors via Two-Dimensional Step-Flow Growth and Drift Region Optimization

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 (Ga2O3) 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 Ga2O3 photosensitive layer, successfully fabricating device-grade Ga2O3/n+-Ga2O3 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 Ga2O3 layer facilitates enhanced carrier drift, resulting in an efficient carrier collection. This work fully explores the potential of Ga2O3 SBPDs for extreme applications and provides an effective design strategy for achieving photovoltaic detectors characterized by zero power consumption, high responsivity, and rapid response.