GaN Nanowire Growth Promoted by In–Ga–Au Alloy Catalyst with Emphasis on Agglomeration Temperature and In Composition

[Image: see text] The crystallographic orientation control of GaN nanowires (NWs) has been widely investigated by varying the V–III ratio. Here, we report the tuning of crystallographic orientation of GaN NWs by varying the composition of indium (In) in gallium–gold (Ga–Au) alloy catalyst using metal–organic chemical vapor deposition (MOCVD). The c-plane GaN thin film and sapphire substrate are used as growth templates. We found that the substrates of same orientation have a negligible influence on the orientation of the GaN NWs. The catalyst composition and the dimensions of alloy droplets determine the morphology of the NWs. The density of the NWs was controlled by tuning the droplet size of the alloy catalysts. With the constant V/III ratio, the crystallographic orientation of the GaN NWs was tuned from m- to c-axis by increasing the In composition inside alloy catalyst.