The Effect of Hydrogen Carrier Gas on the Morphological Evolution and Material Properties of GaN on Sapphire

Abstract

In-situ optical reflectance is used to monitor the morphological evolution of the two-step GaN growth on sapphire. The amount of H2 carrier gas used in the growth is observed to strongly influence the morphological evolution of the low temperature buffer layer and the subsequent high temperature nucleation behavior, which in turn affects the structural and electrical properties of the GaN epitaxial films. The optical reflectance transients correlate with the sizes and distributions of nuclei as observed by AFM.