Thermal Stability of MOCVD and HVPE GaN Layers in H2, HCl, NH3 and N2

Abstract

This work represents a complete study of GaN annealed in H2, HCl, NH3 and N2. The GaN thermal behavior was evaluated by comparison of MOCVD and HVPE samples. The MOCVD films were found to obey a dissociative sublimation mechanism with only gaseous species forming, while the HVPE films reacted with ambient gases to form condensed Ga in addition to the gaseous species. Differences in crystal quality for MOCVD and HVPE samples resulting from the different growth mechanisms account for the observed difference. This analysis of the thermal stability of GaN is extended to include how polarity affects the thermal behavior of GaN during growth and annealing of MOCVD and HVPE films.