Facile integration of an Al-rich Al_1–x In_x N photodetector on free-standing GaN by radio-frequency magnetron sputtering

Al_1−xIn_xN, 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−xIn_xN on a free-standing GaN substrate through direct radio-frequency magnetron sputtering. The optical properties of Al_1−xIn_xN will be enhanced by the polarization effect of a heterostructure composed of Al_1−xIn_xN and other III-nitride materials. An Al_1−xIn_xN/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_0.75In_0.25N/GaN. A rise time of 0.55 s was observed after transient analysis of the device. The prepared Al_1−xIn_xN 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−xIn_xN visible-light photodetectors in optical communication.