Phase-transition-induced superior ultraviolet photodetection of a ZnO/VO2 bilayer

Abstract

A ZnO/VO₂ bilayer film has been successfully grown on a sapphire substrate using pulsed laser deposition (PLD) and magnetron sputtering. The photodetection performance of ZnO is significantly improved across the phase transition temperature of VO₂ both in the presence of a bias and zero bias. At a bias of 1 V, the ultraviolet (UV) photoresponsivity is amplified by approximately 32 times from 0.32 A W⁻¹ to 10.07 A W⁻¹ due to the phase transition of VO₂. Simultaneously, after the phase transition of VO₂, the rise and decay times decrease from 2.49 s and 2.06 s to 0.020 s and 0.032 s, respectively. As for zero-biased performance, the photoresponsivity is also enhanced from 0.53 mA W⁻¹ to 5.56 mA W⁻¹. These results suggest a brand-new mechanism, which can promote the UV photodetection of ZnO via controlling the temperature and provides more degrees of freedom to multifunctional devices.