The diffusion of Sn in relaxed Si1−xGex alloys was studied systematically. In Si1−xGex, the diffusion of Sn was faster than that of Si and Ge, and the results indicated that Sn diffusion in Si and Ge was vacancy-mediated. As Sn was isovalent, no long-range Coulomb interactions existed between Sn atoms and native point defects. Since Sn atoms were larger than Si and Ge atoms, they caused stresses in the SiGe lattice. The present findings were explained by attractive elastic interactions caused by the pairing of Sn atoms with vacancies; relaxing the stresses and repulsive elastic interactions between Sn atoms and self-interstitials.

Elastic Interactions and Diffusion of Sn in Si1-xGex Systems. I.Riihimäki, A.Virtanen, H.Kettunen, P.Pusa, P.Laitinen, J.Räisänen, Isolde: Applied Physics Letters, 2007, 90[18], 181922