A Fast Self-Powered Solar-Blind Ultraviolet Photodetector Realized by Ga2O3/GaN PIN Heterojunction with a Fully Depleted Active Region

Abstract

Ga2O3 is a wide bandgap semiconductor suitable for solar-blind photodetection, but there exist two issues for Ga2O3-based photodetectors: first, it is difficult to achieve reliable p-type Ga2O3 and therefore form a homojunction photodetector, and the other is related with the slow response speed of Ga2O3-based photodetectors. In this work, a self-powered solar-blind photodetector with a fast response using a p-GaN/i-Ga2O3/n-Ga2O3 (pin) heterojunction with a fully depleted active region is realized, where i-Ga2O3 serves as the main light-absorbing active region. The device exhibits good self-powered characteristics with a high responsivity of 72 mA W−1, a high photo-to-dark current ratio of 18 800, a high specific detectivity of 3.22 × 1012 Jones, and a fast response speed with a rise time/decay time of 7 ms/19 ms, respectively, without an external power supply. A detailed study of the interfacial electronic structure between p-GaN and i-Ga2O3 reveals a conduction band offset and valence band offset of 0.16 and 1.37 eV, respectively. Meanwhile, it has a large built-in potential of 1.03 eV and a wide depletion region width of 235 nm in the i-Ga2O3 side of heterojunction. It is believed that excellent device performance comes from a suitable energy band structure and wide depletion region.