Single-crystal GaN layers have been obtained by nitridingβ-Ga2O3 films in NH3 atmosphere.The effect of the temperature and time on the nitridation and conversion of Ga2O3 films have been investigated.The nitridation process results in lots of holes in the surface of films.The higher nitridation temperature and longer time can promote the nitridation and improve the crystal quality of GaN films.The converted GaN porous films show the single-crystal structures and lowstress,which can be used as templates for the epitaxial growth of high-quality GaN.