1. Introduction . With the rapid development of the semiconductor industry, third-generation wide-bandgap semiconductor materials and devices are being widely used in solid-state lighting, optical storage, electronic power devices, and other fields [ 1 ]. Group III nitride semiconductor materials, including InN, GaN, AlN, their ternary alloys AlGaN, and InGaN, offer a broad range of light-emitting wavelengths, ranging from deep ultraviolet to infrared [ 2 ]. These materials exhibit exce...