Two-step growth of m-plane GaN epilayer on LiAlO 2 (1 0 0) by metal-organic chemical vapor deposition

Abstract

The m-plane GaN (1 1¯ 0 0) epilayers have been grown on LiAlO 2 (1 0 0) substrate by a two-step growth method using a metal-organic chemical vapor deposition (MOCVD) system. The GaN buffer layer is introduced to overcome the drawbacks of thermal instability of LiAlO 2 (LAO), and to relieve the strains due to large thermal mismatch between LAO and GaN. The results of X-ray diffraction (XRD) and polarized Raman scattering spectra demonstrate that the GaN (1 1¯ 0 0) epilayer is single crystal as the growth temperature of the buffer layer is in the range of 850–950 °C. Moreover, it is found that the surface nitridation process on LAO substrate can result in the formation of the GaN poly-crystalline films, which is due to the unintentional growth of a thin layer of c-phase AlN on LAO surface.