P–Cu₂O QDs/Sn:α-Ga₂O₃ Nanorod Array for High-Sensitivity and Fast-Speed Solar-Blind Photodetectors

Self-powered solar-blind detectors have important potential applications in military and civil fields, but their low responsivity and slow response speed limit their practical applications. Regulating the internal barrier height by doping is an effective means of optimizing the performance of self-powered detectors. In this work, a self-powered solar-blind detector with a Cu2O QDs/Sn:α-Ga2O3 nanorod array with an average diameter of 200–500 nm was prepared by a hydrothermal process and simple spin coating. In the absence of electrical power, the responsivity of the device reached 6.574 mA/W at a 254 nm light stimulation, which increased by 11.27 times that of the undoped photodetector. At the same time, the device also has a short optical response time of 0.2s/0.3s. These results can be attributed to the following reasons. (1) Sn doping increases the carrier concentration, thereby increasing the conductivity of α-Ga2O3. (2) In the interfacial depletion region of Cu2O QDs/Sn:α-Ga2O3, increasing the height of the built-in barrier can effectively separate the photogenerated electron–hole pairs. This work provides a simple and effective way to construct a high-performance self-powered solar-blind photodetector.