ZnO nanostructure-assisted growth of (0002)-oriented GaN thin films by laser molecular beam epitaxy

Abstract

Vertically aligned zinc oxide (ZnO) nanostructures (NS) have been fabricated without any catalyst on Si (100) and sapphire (0002) substrates using high-pressure-assisted pulsed laser deposition technique. It has been observed that the substrate plays a crucial role in deciding the morphology and optical quality of the nanostructures, wherein ZnO NS on Si substrate exhibit better luminescence characteristics as compared to those grown on sapphire substrate. Gallium nitride (GaN) layers are grown using a customized laser molecular beam epitaxy system and the effect of an intermediate layer in the form of vertically aligned ZnO NS is analyzed. A comparative study is performed with GaN layers grown on ZnO NS-coated Si, bare Si, and bare sapphire substrate. The structural and room temperature photoluminescence properties of the GaN layer significantly improve when grown on ZnO-NS/Si substrates as compared to bare sapphire and Si substrate.