Highly (111)-oriented Ge thin films on insulators formed by Al-induced crystallization

Abstract

111)-oriented Ge thin films on insulators are essential for advanced electronics and photovoltaic applications.We investigate Al-induced crystallization of amorphous-Ge films (50-nm thickness) on insulators focusing on the annealing temperature and the diffusion controlling process between Ge and Al.The (111)-orientation fraction of the grown Ge layer reaches as high as 99% by combining the low-temperature annealing (325 C) and the native-oxidized Al (AlO x ) diffusioncontrol layer.Moreover, the transmission electron microscopy reveals the absence of defects on the Ge surface.This (111)-oriented Ge on insulators promises to be the high-quality epitaxial template for various functional materials to achieve next-generation devices.