Charge Transfer Doping Enabled High-Performance Deep-Ultraviolet Photodetectors Based on CuI/β-Ga2O3 Heterostructures for Deep-Ultraviolet Optical Communication

Abstract

In this work, we report on self-driven deep-ultraviolet (DUV) photodetectors composed of CuI/β-Ga₂O₃ heterostructures, whose photodetection performance can be significantly boosted by charge transfer doping of CuI. The incorporation of MoO₃ with a high work function induces spontaneous electron withdrawal from CuI towards MoO₃, thereby increasing the work function of CuI and ultimately amplifying the junction barrier of the CuI/β-Ga₂O₃ heterostructure. As a consequence, the photoresponse parameters in terms of photovoltage responsivity, photocurrent responsivity, and specific detectivity are largely improved from 1.47×10⁸ V/W, 8.41 mA/W, and 8.53×10¹¹ Jones to as high as 9.87×10⁸ V/W, 20.59 mA/W, 3.01×10¹² Jones, respectively. The optimal device displays a large current on/off ratio of exceeding 2.0×10 4 , an ultralow dark current of less than 1×10^-13 A, a high DUV/visible rejection ratio of 1.45×10⁴ , and a relatively rapid response speed of 33.5/49.7 ms, as well. A device assembled on a plastic substrate exhibits robust mechanical flexibility. What is more, the good DUV photodetection performance enables the device to be utilized in a DUV optical communication system, functioning as a light receiver to deliver a text signal. It is expected that this DUV photodetector will acquire utilizations in future DUV photoelectric systems.