Selective Growth of GaN Rods on the Apex of GaN Pyramids by Metal Organic Vapor Phase Epitaxy

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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 \langle 1\bar{1}00\rangle directions. The GaN rods had triangular cross section enclosed with (11\bar{2}2), (\bar{1}\bar{1}22), 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.
2013-01-25