Gallium K-edge EXAFS measurements on cubic and hexagonal GaN

Abstract

The microstructure of undoped cubic and hexagonal GaN films is studied using temperature dependent Ga K-edge EXAFS measurements (10K-290K). The microstructure around the Ga atom is distorted due to a splitting of the second nearest neighbor shell, which consists of Ga atoms. This splitting results in an additional Ga path at a distance longer than expected by 0.8±0.05 Å and is attributed to local lattice relaxation around nitrogen vacancies. From the temperature dependence of the DW factors for the 2nd nearest neighbor shell of Ga, the Einstein temperature is equal to 318±25K.