We report on the growth and characterization of microscale GaN structures selectively grown on the apexes of hexagonal GaN pyramids. SiO 2 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 f1101g 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 SiO 2 film because of the roughness and nonuniform thickness of the SiO 2 film. #
We report on the growth and characterization of GaN rods selectively grown on the apex of hexagonal GaN pyramids. SiO2 near the apex of the hexagonal GaN pyramids was removed by an optimized photolithography process and subsequently subjected to Au deposition and selective growth of GaN rods by metal organic vapor phase epitaxy (MOVPE). It was observed that there were preferred GaN rods orientations toward <1100> directions. The GaN rods had triangular cross section enclosed with (1122), (1122), and (0001) side facets. A particular feature was that each rod has sharp edge at its very end. We found that the GaN rods could be formed not by vapor–liquid–solid (VLS) process but Ga–Au intermediate state. This work opens up new growth methods for position and density controlled III–nitride nano- and micro-structures which have potential use in high functional devices, such as field emitters and gas sensors.
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