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.