GaSe/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub> heterojunction based self-powered solar-blind ultraviolet photoelectric detector

Abstract

UV photodetectors have the advantages of high sensitivity and fast response speed. As an ultra-wide bandgap semiconductor, gallium oxide (Ga<sub>2</sub>O<sub>3</sub>) plays an extremely important role in detecting deep ultraviolet. It can form a typical type-II heterostructure with GaSe, promoting carrier separation and transport. In this work, Ga<sub>2</sub>O<sub>3</sub> epitaxial films are grown on sapphire substrates by plasma-assisted chemical vapor deposition (PECVD). The GaSe films and GaSe/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub> heterojunction photodetectors are grown on gallium oxide films by Bridgeman technology. The detector has a good response to deep ultraviolet light, the dark current of the device is only 1.83 pA at 8 V, and the photocurrent reaches 6.5 nA at 254 nm. The UVC/Visible (254 nm/600 nm) has a high rejection ratio of about 354. At very small light intensities, the responsivity and detection can reach 1.49 mA/W and 6.65× 10<sup>11</sup> Jones, respectively. At the same time, due to the photovoltaic effect formed by the space charge region at the junction interface, the detector exhibits self-powered supply performance at zero bias voltage, and the open-circuit voltage is 0.2 V. In addition, the detector has a very good sensitivity. The device can respond quickly, whether it is irradiated with different light intensities under constant voltage, or with different voltages under constant light intensity, . It can respond within milliseconds under a bias voltage of 10V. This work demonstrates the enormous potential of heterojunctions in photoelectric detection by analyzing the photophysical and interface physical issues involved in heterojunction photodetectors, and provides a possibility for detecting the deep ultraviolet of gallium oxide.