Improvement in aligned GaN nanowire growth using submonolayer Ni catalyst films

Abstract

We report a route to ultrahigh-density and highly aligned single-crystalline GaNnanowires on sapphire by employing ultrathin Ni catalyst films with submonolayer thickness. The nanowire density and the degree of alignment were found to be highly sensitive to changes in the Ni catalyst film thickness below 1 nm , a regime rarely explored in catalyzed nanowiregrowth before. For submonolayerNifilms on sapphire, high activation energy for Nidiffusion on sapphire surface is attributed to the formation of high-density and ultrasmall Ni islands with a narrow size distribution, which in turn leads to high-density and highly aligned GaNnanowires.