Anisotropic effect of biaxial strain on phosphorus diffusion in silicon

In $\mathrm{Si}∕{\mathrm{Si}}_{1\ensuremath{-}x}{\mathrm{Ge}}_{x}$ heterostructures, the lattice mismatch induces $x$-dependent strains in neighboring layers. The effect of such a biaxial strain on the migration of phosphorus dopants in silicon has been investigated theoretically. The interstitial-based diffusion process of phosphorus can be divided into sequences of various migration steps. A clear preference of diffusion along the compressed direction is found. The applied strain has been found to lower the activation energies of most of the discussed steps and thus enhance the overall diffusivity.