Crystalline Structure and the Role of Low-Temperature-Deposited AlN and GaN on Sapphire Revealed by X-Ray CTR Scattering and X-Ray Reflectivity Measurements

Abstract

Crystalline and morphological quality of low-temperature (LT)-deposited and annealed AlN and GaN thin layers were investigated by X-ray crystal truncation rod (CTR) scattering and X-ray reflectivity measurements and atomic force microscope (AFM) observation. It was revealed that the LT-AlN layer was more uniform in terms of the crystalline structure and the layer thickness than the LT-GaN layer, before and after annealing. It suggests that LT-AlN is more suitable as a buffer layer between sapphire substrate and GaN.