Direct growth of GaN on sapphire with non-catalytic CVD graphene layers at high temperature

Today, heteroepitaxial GaN films on sapphire have focused on conventional two-step growth process using low temperature GaN buffer layer. Here, we show the direct growth of GaN films on sapphire by using a graphene layer at high temperature, which simplified the GaN growth process. The graphene is directly synthesized on non-catalytic sapphire substrate by chemical vapor deposition without problematic transfer processes, using C2H4 as a carbon source at the temperature of 1200 oC. The synthesized graphene has been characterized by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM). We have compared the GaN grown on sapphire with and without graphene. The single crystal, smooth surface GaN films has been obtained on sapphire with graphene, and the nucleation of GaN films has been discussed. The GaN films illuminated high near-band-edge emission and good ultraviolet photosensor. It demonstrates that graphene is a potential, useful buffer layer for heteroepitaxy of high quality GaN films.