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

• Published in: Applied surface science 2024-06, Vol.659, p.159901, Article 159901
• Main Authors: Zhu, Ying, Zhang, Yiwen, Li, Bowen, Xia, Guangrui (Maggie), Wen, Rui-Tao
• Format: Article
• Language: English
• Subjects: Ge/Si interface; Interdiffusion; Kirkendall effect
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2024.159901

•The as-grown Ge on Si (001) wafer showed islands of GeSi interdiffusion layer with a fixed composition, which was confirmed by cross-section and plan-view TEM.•The island GeSi interdiffusion layer gradually vanished as the annealing temperature increased, resulting in a dominant diffusion of Si into the Ge epi-layer. 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 with the increase of annealing temperature.•Effective interdiffusivity was extracted by Boltzmann-Matano analysis, which indicated that the GeSi interdiffusion at the interface was dominated by dislocation-mediated interdiffusion. 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.