Facile integration of an Al-rich Al 1–x In x N photodetector on free-standing GaN by radio-frequency magnetron sputtering

Al 1− x In x N, a III-nitride semiconductor material, is currently of great research interest due to its remarkable physical properties and chemical stability. When the Al and In compositions are tuned, its band-gap energy varies from 0.7 eV to 6.2 eV, which shows great potential for application in photodetectors. Here, we report the fabrication and performance evaluation of integrated Al 1− x In x N on a free-standing GaN substrate through direct radio-frequency magnetron sputtering. The optical properties of Al 1− x In x N will be enhanced by the polarization effect of a heterostructure composed of Al 1− x In x N and other III-nitride materials. An Al 1− x In x N/GaN visible-light photodetector was prepared by semiconductor fabrication technologies such as lithography and metal deposition. The highest photoresponsivity achieved was 1.52 A⋅W −1 under 365 nm wavelength illumination and the photodetector was determined to have the composition Al 0.75 In 0.25 N/GaN. A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al 1− x In x N visible-light photodetector had a low dark current, high photoresponsivity and fast response speed. By promoting a low-cost, simple fabrication method, this study expands the application of ternary alloy Al 1− x In x N visible-light photodetectors in optical communication.