Improved Surface Quality of the Metal-Induced Crystallized Ge Seed Layer and Its Influence on Subsequent Epitaxy

Abstract

Al-induced crystallized Ge (AIC-Ge) seeded epitaxy is a promising way to fabricate functional materials on amorphous substrates such as glass or polymer sheets. However, the AIC-Ge had difficulty in producing a continuous thin film without forming fine-grain Ge islands stacked on the surface. In this paper, we solved this problem by initially preparing thicker Ge (100 nm) than Al (50 nm) and then removing excess Ge islands using a unique etching technique. The resulting AIC-Ge allowed for a high (111) orientation (96%) and large grains (>100 μm). Transmission electron microscopy demonstrated that an AIC-Ge-seeded Ge layer, grown by molecular-beam epitaxy at 500 °C, was of high quality reflecting the annihilation of Ge islands. This method opens up the possibility for synthesizing Ge, GaAs, and other functional materials on an amorphous substrate.