Self-organized growth of catalyst-free GaN nano- and micro-rods on Si(111) substrates by MOCVD

Our study shows the impact of the process parameters: predose before AlN buffer deposition, SiNx deposition time, GaN growth temperature and silane injection time on growth and morphology of GaN nanowires (NWs) formed by a self-organized mechanism on a silicon substrate. We determined a process parameter window for successful GaN NW growth and show how the variation of studied parameters changes the NW morphology and density. The optimization of these process parameters led to high-density straight GaN NWs, aligned perpendicular to the substrate. The use of a preflow before AlN buffer deposition was found to be important for the successful NW formation, and most interestingly, led to a difference in structural morphology for ammonia and TMAl predose. (C) 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim