The effect of biaxial strain on impurity diffusion in Si and SiGe

Results from diffusion studies of different impurities in biaxially strained Si and Si1 − xGex for low x-values will be presented. The structures are all molecular-beam epitaxy (MBE) grown on strain-relaxed Si1 − xGex layers, and the impurity profiles are introduced during growth. We have in particular been concerned with the effect of biaxial strain (compressive and tensile) on the diffusion of pure vacancy-assisted diffusers (Sb and, partly, Ge) and pure interstitial-assisted diffusers (B and P). It is found that compressive biaxial strain retards the diffusion of the interstitial-assisted diffusers, whereas tensile biaxial strain enhances the diffusion of these impurities. The opposite is the case for the vacancy-assisted diffusers.