Growth and characterization of GaN epilayers on chemically etched surface of 3C-SiC intermediate layer grown on Si(111) substrate

High-quality GaN films were grown on Si(111) substrate using 3C-SiC intermediate layer by metalorganic chemical vapor deposition. The 3C-SiC intermediate layer was grown on the Si(111) substrate by chemical vapor deposition using tetramethylsilane as a single source precursor. We have investigated the effect of chemical etching of SiC intermediate layer surface under different conditions. SiC layer was etched using potassium carbonate (K2CO3), hydrochloric acid (HCl), and hydrofluoric acid (HF), respectively. The surface roughness of 3C-SiC intermediate layer decreased as the chemical etching time was increased. GaN films with local atomically flat surfaces were obtained and the X-ray diffraction full-width at half maximum of (0002) peak was 664.5 arcsec for a 1.56 mum thick film. The reduced SiC surface roughness decreased the defect density in GaN epilayers. In the photoluminescence spectra at room temperature. the yellow band emission peak at around 2.2 eV disappeared.