Morphological and Microstructural Evolution and Related Impurity Incorporation in Non-Polar a-Plane GaN Grown on r-Sapphire Substrates **Supported by the National Natural Science Foundation of China under Grant No 61204006, and the Fundamental Research Funds for the Central Universities under Grant No K50511250002.

Abstract

Effects of the growth temperature on morphological and microstructural evolution of a-plane GaN films grown on r-plane sapphires by metal organic chemical vapor deposition are investigated by atomic force microscopy and secondary ion mass spectroscopy (SIMS). Surface morphology, structural quality and related impurity incorporation are very sensitive to the growth temperature. A significant difference of yellow luminescence is observed and attributed to the incorporation of carbon into GaN films, which is confirmed by SIMS analysis. Our results show that the sample with triangular-pit morphology has significantly higher concentrations of oxygen than the other sample with pentagon-like pit morphology, which is induced by the existence of an N-face in triangular pits.