Spontaneous transition in preferred orientation of GaN domains grown on r-plane sapphire substrate from [112¯] to [0001

Abstract

GaN films were grown at 550 °C and subsequently at 1040 °C on sapphire (101¯2) (r-plane) substrates by using hydride vapor phase epitaxy with different layer thicknesses. As the thickness of a low-temperature-grown GaN layer was increased, a preferred orientation of GaN grown at 1040 °C changed from [112¯0] to [0001]. A detailed atomistic model reveals that this spontaneous transition in preferred orientation is due to the formation of inversion domain boundaries and stacking faults. This result has a significant implication that tailoring film characteristics in terms of controllability of preferred orientation may be possible independent of substrate orientation.