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) diffusion-control 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. © 2012 American Institute of Physics.