A dual-color ultraviolet-visible photodetector based on a Cu2O/GaN heterojunction: high responsivity, fast response, and high spectral selectivity

Abstract

In this study, a Cu₂O/GaN heterojunction based dual-color photodetector was fabricated using electrochemical deposition. The photodetector exhibits high spectral selectivity for both ultraviolet and visible light. When illuminated from the GaN side, the device demonstrates a maximum responsivity of 45 A W⁻¹, an external quantum efficiency of 10⁴, a fast rise time of 30 μs and a decay time of 190 μs at a −10 V bias under UV light. Conversely, when illuminated from the Cu₂O side, the detection range shifts to 500–630 nm, achieving a responsivity of 60 mA W⁻¹ and a rise time of 36 μs. Additionally, the photodetector exhibits significant self-powered dual-band detection capabilities. Material characterization results from XRD, XPS, SEM, and other techniques indicate that the device's excellent spectral selectivity and photo-detection performance are primarily attributed to the high-quality Cu₂O thin film, the well-formed Cu₂O/GaN interface, and the high visible light absorption coefficient of Cu₂O. Our research provides a new approach for fabricating high-performance photodetectors with dual-band detection capabilities.