Influence of the Strain of AlN Buffer Layer on the Strain Evolution of GaN Epilayer Grown on 3-in 6H-SiC Substrate

The influence of the strain of AlN buffer layers on the strain evolution of GaN epilayers grown on 3-in 6H-SiC substrates by metal-organic chemical vapor deposition was investigated by double-crystal X-ray diffractometry, and Raman scattering spectra. It was found that the tensile strain of the GaN epilayers mainly decreases with the strain of the AlN buffer layers varied from tensile to compressive. A model based on the strain evolution during the epitaxial growth is proposed to provide a valuable reference for the massive production of large scale and high quality GaN epilayers.