“…Based on their improved techniques, the high-quality materials, such as GaN, InN, InAlN, and AlGaN were obtained, and the corresponding advanced devices, such as high electron mobility transistor, vertical structure LEDs, and LDs, were successfully fabricated. Zhang et al [5] present a very attractive subject, GaN-based optoelectronic devices on Si substrate, which would act as a platform for mature Si-based integrated circuits and even for optoelectrical integration. Besides the typical III-V GaN-based and II-VI ZnO-based compounds, some other wide bandgap semiconductors are also investigated in this special issue.…”