Boron diffusion in strainedSi1−xGexepitaxial layers

B diffusion in ${\mathrm{Si}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ge}}_{\mathit{x}}$ strained layers on Si was studied as a function of annealing temperature and Ge content and is shown to be characterized by lower diffusivity as compared to unstrained Si. The influence of the Ge content on the dopant diffusion was also measured, demonstrating that the diffusivity of the B atoms is reduced with increasing Ge fraction in the strained layer. The reduced diffusivity of B in the strained ${\mathrm{Si}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Ge}}_{\mathit{x}}$ relative to the dopant diffusivity in unstrained Si is attributed to the change in the charged point-defect concentration caused by band-gap narrowing. We find good agreement between the measured and simulated diffusivity using the known band-gap for the strained layers.