Current mechanism and interface states in Ga2O3 MSM solar-blind photodetector

The (3-Ga2O3 metal-semiconductor-metal (MSM) solar-blind photodetectors (PDs) have been widely reported due to their simple preparation and low dark current, and have presented significant potential in the field of UVC photodetection under severe temperature environments. The properties of Ga2O3 MSM-PDs were closely related to the interfacial traps. However, the carrier mechanism, the role of interfacial traps and the transient process between dark and UV irradiation have not been fully revealed. In this work, the temperature-dependent I-V and It curves, and frequency-dependent C-V curves were utilized to investigate the intrinsic carrier transport mechanism. It was found that the reverse dark current was dominated by Poole-Frenkel (PF) emission with trap depth of 0.58 eV at Metal/Semiconductor interface, whose density increased and capture/emission time decreased with temperature. Under UVC light illumination, thermionic emission (TE) with Gaussian distribution of inhomogeneous Schottky barrier height (SBH) dominated the carrier transportation process. The elevation of effective SBH declined photocurrent at high temperatures. The capture and emission of carriers in traps determined the switching between TE and PF mechanisms upon the UVC illumination ON and OFF. Our work provides a fundamental current mechanism for better understanding Ga2O3-based MSM PDs.