Elastic interactions and diffusion of Sn in Si1−xGex systems

Diffusion of Sn in relaxed Si1−xGex alloys has been studied systematically. In Si1−xGex, diffusion of Sn is faster than that of Si and Ge, and the results indicate that Sn diffusion in silicon and germanium is vacancy mediated. As Sn is isovalent, no long range Coulomb interactions exist between Sn atoms and native point defects. Since Sn atoms are larger than Si and Ge atoms, they cause stress in the SiGe lattice. The present findings are explained by attractive elastic interactions caused by pairing of Sn atoms with vacancies relaxing the stress and repulsive elastic interactions between Sn atoms and self-interstitials.