Cu2O/Ga2O3 pn-junction photodetector with low dark current and high detectivity

Cu₂O is a natural p-type semiconductor material with a high optical absorption coefficient in the visible range. It possesses characteristics such as abundant raw materials, low cost, non-toxicity, no pollution, and high theoretical photoelectric conversion efficiency. At present, achieving p-type doping in Ga₂O₃ is challenging, making the preparation of Ga₂O₃ homojunction photodetectors a significant recent challenge. Combining n-Ga₂O₃ with p-type semiconductors to prepare pn heterojunction photodetectors offers an effective alternative approach. Based on this, this article combines electrochemically grown Cu₂O with magnetron sputtered amorphous Ga₂O₃ to prepare a low dark current and high detectivity Cu₂O/Ga₂O₃ ultraviolet visible heterojunction photodetector. The photodetector exhibits a low dark current of 1.58 × 10⁻⁹ A and a high rectification ratio of 10³ under a −5 V bias. It shows a peak responsivity of 4.26 A W⁻¹ and an EQE of 977.91% at a wavelength of 540 nm. Additionally, the photodetector has a detectivity of 1.17 × 10¹² Jones, an NEP of 4.80 × 10⁻¹³ W Hz^−1/2, and rise and fall times of 0.49 and 0.70 s, respectively. Comparing it with Cu₂O PD, it is demonstrated that the reason for the improvement of the photodetector is due to the built-in electric field formed by the heterojunction, which can effectively separate electron hole pairs and suppress their recombination. This work provides a simple and effective method for preparing Cu₂O heterojunction photodetectors.