Impurity diffusion through strained semiconductors

In this paper we study the effect which stresses in crystalline solids (such as semiconducting crystals) have on the diffusion of impurities through them. We modify two models describing key mechanisms for diffusion in crystals, namely the interstitial and kick-out diffusion models, to incorporate some of the effects of stress. In particular, we consider a paradigm problem in which the stress is due to the presence of a masking film on part of the surface, numerically solving the governing equations subject to boundary and initial conditions which model in-diffusion near a mask edge and giving an asymptotic description of the large-time time behaviour. Some of the calculated impurity contours have an unusual character, though all of the results are consistent with intuitive expectations.