Controlled growth and surface morphology evolution of m-oriented GaN faceted-domains on SiO₂-patterned m-plane sapphire substrates

m-oriented GaN faceted-domains were grown on SiO₂-patterned m-plane sapphire substrates with no low-temperature-grown buffer layers, and their surface morphology evolution was investigated. The preferred crystallographic orientations of GaN domains are found to be sensitively influenced by substrate temperature. The growth rate of m-oriented GaN faceted-domains along the c-direction is found to be significantly suppressed after filling up the circular-shaped window regions. Our simple model calculation reveals that this can be explained by the minimization of surface energy increment per volume increment, and that the growth along the c-direction is energetically not favored until the domain reaches a critical size.