Selective Growth of Microscale GaN Pyramids on Apex of GaN Pyramids

We report on the growth and characterization of microscale GaN structures selectively grown on the apexes of hexagonal GaN pyramids. SiO2 near the apex of the hexagonal GaN pyramids was removed by an optimized photolithography process and subsequently subjected to selective growth of micro scale GaN structures by metal organic vapor phase epitaxy (MOVPE). The pyramidal GaN microstructures which have semi-polar {101} facets, were formed only on the apexes of lower GaN pyramids. The size of the selectively grown micro GaN structures was easily controlled by the growth time. Reduction of the threading dislocation density was confirmed by transmission electron microscopy (TEM) in the selectively regrown micro GaN structures. However, stacking faults developed near the edge of the SiO2 film because of the roughness and nonuniform thickness of the SiO2 film.