Nucleation characteristics of GaN nanorods grown on etched sapphire substrates by hydride vapor phase epitaxy

Effect of etched sapphire substrates on the nucleation characteristics of GaN nanorods was investigated. c-plane sapphire substrates (0 . 3^{{ring operator}}-miscut toward m-plane (1 0 over(1, -) 0)) were etched in situ by HCl at 1015 ^{{ring operator}} C in the reactor of hydride vapor phase epitaxy (HVPE). GaN nanorods were grown on these etched sapphire substrates by using HVPE. Etched sapphire substrates had many step structures with different heights. Most of GaN nanorods were grown on the step regions and rarely observed on the terrace regions. The preferred nucleation positions were, however, found to extend to terrace regions if the growth temperature was increased.