Influence of Rapid Thermal Annealing on Ge-Si Interdiffusion in Epitaxial Multilayer Ge_0.3Si_0.7/Si Superlattices with Various GeSi Thicknesses

Abstract

Ge-Si interdiffusion in epitaxial multilayer Ge0.3Si0.7/Si superlattices (SLs) is investigated as a function of varying GeSi layer thicknesses and under different annealing temperatures. The results show that rapid thermal annealing (RTA) below 800°C has a negligible effect on Ge-Si interdiffusion. Interdiffusion in Ge0.3Si0.7/Si SLs is observed at temperatures higher than 900°C. Furthermore, the interface of the GeSi/Si becomes diffuse when annealed at 1000°C because of rapid Ge-Si interdiffusion. It is observed that the initial 5 nm thick GeSi layer is increased by 4.9 nm, and the Ge concentration decreases from 30% to 16.25%. The obtained results provide a practical and reliable guidance for GeSi/Si SLs interdiffusion, especially for gate-all-around (GAA) nanowire (NW)/nanosheet (NS) device design, processing and application.