Evolution of GeSi islands in epitaxial Ge-on-Si during annealing

Abstract

Epitaxial growth of Ge on Si has been widely studied for photonic and electronic applications. However, GeSi interdiffusion during the growth or annealing deteriorates the performance of the devices. This paper explores the evolution of the interface and GeSi interdiffusion upon post-annealing. We found the GeSi interdiffusion islands with concentration plateaus gradually disappeared upon annealing and the interdiffusion became more pronounced in the Ge layer. Moreover, by using a thin layer of SiO2 as a reference, we directly visualized the Kirkendall phenomenon, i.e., the migration of the Ge/Si interface towards the Si substrate after the annealing. Effective interdiffusivity at 900 °C was extracted using Boltzmann-Matano analysis, which indicated that the GeSi interdiffusion at the interface was dominated by dislocation-mediated interdiffusion.