Morphology Control of Hot-Wall MOCVD Selective Area Grown Hexagonal GaN Pyramids

Morphological variations of gallium polar (0001)-oriented hexagonal GaN pyramids grown by hot-wall metal organic chemical vapor deposition under various growth conditions are investigated. The stability of the semipolar {11̅02} and nonpolar {11̅00} facets is particularly discussed. The presence of the {11̅02} facets near the apex of the pyramid was found to be controllable by tuning the absolute flow rate of ammonia during the growth. Vertical nonpolar {11̅00} facets appeared in gallium-rich conditions, which automatically were created when the growth time was prolonged beyond pyramid completion. The result was attributed to a gallium passivation of the {11̅00} surface.