Optical and electrical properties of GaN films grown on alpha-Al2O3(0 0 0 1) substrates by GSMBE using In-doping method were investigated. It was found that both of them were improved, compared to those of a nondoped GaN one. mu-PL results at 20 K indicated that In-doped films emit luminescence more uniformly than that of a nondoped one. Furthermore. Hall effect measurements at 300 K showed higher electron mobility of In-doped samples than that of a nondoped one. It is suggested that the presence of In during the growth of GaN films plays a role in reducing the number of structural imperfections to improve the optical and electrical properties.