Self-powered ultraviolet photodetector based on CuGaO/ZnSO heterojunction

A heterojunction photodetector formed by CuO–Ga (CuGaO) and ZnO–S (ZnSO) thin film has been fabricated by solution combustion synthesis and magnetron sputtering. The band structure of CuGaO/ZnSO heterojunction is studied by using X-ray photoelectron spectroscopy. The valance band offset of CuGaO/ZnSO is calculated to be 0.38 eV by using the Kraut equation. The device shows a responsivity of 3.78 mA/W and a detectivity of 1.16 × 10¹⁰ Jones under 365 nm ultraviolet (UV) illumination, when operated as a self-powered (zero bias) UV photodetector. The average rise and decay times can be calculated as 0.034 s and 0.027 s, respectively. The CuGaO/ZnSO heterojunction is a promising candidate for the application in self-powered UV photodetection.