Density and morphology adjustments of gallium nitride nanowires

This paper presents the morphology and density adjustments of GaN nanostructures via CVD process. GaN nanostructure growth has been carried out using Ga and NH3 as source materials with various catalyst materials, such as Au, Ni, Ag, and Fe between 800 and 1100 °C. The investigation has focused on the effects of process parameters, such as growth temperature and catalyst materials on the GaN nanowire morphology and density. Low temperature (<950 °C) growth runs resulted in microscale-faceted crystals and short nanorods regardless of the catalyst type or reactor pressure. Conversely, high temperature (1100 °C) growth runs resulted in ultra-dense interwoven long nanowires with multi-prong growth mechanism. A detailed analysis for the transition from microscale-faceted crystals to ultra-dense multi-prong-grown GaN nanowires is provided. Furthermore, electrical characteristics of the grown nanowires have been demonstrated through a very efficient fabrication scheme. Consequently, multi-prong growth mechanism reduces catalyst contamination and produces high density of long nanowires, which is very crucial for scale-up manufacturing opportunities.