(Invited) High-Mobility Ge on Insulator (GOI) by SiGe Mixing-Triggered Rapid-Melting-Growth

Abstract

High-quality orientation-controlled Ge on insulator (GOI) structures are essential to realize high-performance thin-film transistors (TFTs) and epitaxial templates for multifunctional 3-dimensional large-scale integrated circuits (3D-LSIs). We have investigated the Si-seeding rapid-melting process and demonstrated formation of giant Ge stripes with (100), (110), and (111) orientations on Si (100), (110), and (111) substrates, respectively, covered with SiO2 films. We revealed that crystallization is triggered by Si-Ge mixing in the seeding regions in this process. Based on this mechanism, we have proposed a novel technique to realize orientation-controlled Ge layers on transparent insulating substrates by using Si artificial micro-seeds with (100) and (111)-orientations. This achieved epitaxial growth of single crystalline (100) and (111)-oriented Ge stripes on quartz substrates. The transmission electron microscopy observations revealed no-defects in the laterally grown Ge regions. The Ge layers showed a high hole mobility exceeding 1100 cm2/Vs owing to the high crystallinity. This novel SiGe mixing-triggered growth technique opens up the possibility of the next-generation TFTs and multifunctional 3D-LSIs.