Ultrasensitive Self-Powered Deep-Ultraviolet Photodetector Based on In Situ Epitaxial Ga2O3/Bi2Se3 Heterojunction

The Ga2O3-based deep-ultraviolet photodetectors (DUV PDs) possess great potential due to the suitable bandgap and desired stability. However, the compulsive external bias and the undesired response speed severely limit its large-scale implementations. Herein, we report a highly efficient self-powered Ga2O3/Bi2Se3 heterojunction PD, fabricated through an in situ epitaxial deposition process. The Ga2O3 and Bi2Se3 films are found to present a van der Waals bonding with great orientation crystallinities. Under the self-powered mode, the device presents a stable and favorable photoresponsivity with an ultralow dark current of 3.12 pA and an excellent detectivity of 6.23 x 10(13) Jones under 245-nm light illumination. Moreover, the device presents an ultrafast rise and decay response time of 0.6 and 1.2 ms, which achieves more than four orders of magnitude reduction compared to the Ga2O3 photoconductor. Such excellent improvement can be attributed to the high-quality Ga2O3/Bi2Se3 heterojunction and the high carrier mobility of Bi2Se3, which is beneficial for improving the separation and transfer efficiency of the electron-hole pairs. This work provides a new direction for developing the Ga2O3 based DUV PD.