Dependence of the surface, the structural, and the optical properties on the thickness of the AIN buffer layer for GaN epilayers grown on sapphire substrates

Atomic force microscopy (AFM), double crystal rocking curve (DCRC), scanning electron microscopy (SEM), and photoluminescence (PL) measurements on GaN epilayers grown with various thicknesses of the AIN buffer layer were carried out to investigate the surface, the structural, and the optical properties of the GaN epilayers. The results of the AFM, DCRC, SEM, and PL measurements showed that the GaN epilayer grown on a 3.4 nm AIN buffer layer had the best quality. These results indicate that GaN active layers grown on 3.4 nm AIN buffer layers hold promise for potential applications in optoelectronic devices operating in the blue-green region of the spectrum.