Abstract
AbstractIn the present work the results of theoretical analysis of the process of diffusion of covalently bonded atoms (interstitial oxygen atoms) in Si1‐xGex alloys are presented. The diffusion coefficient (activation energy and preexponential factor) was calculated by means of quantumchemical simulations (NDDO PM5) and the dependences of the activation energy and preexponential factor on Ge atoms concentration (x) were analyzed with the use of the percolation theory. It is shown that a significant decrease in the diffusion coefficient of interstitial oxygen atoms in Si1‐xGex (x<0.05) compared to the value in pure silicon is caused not only by changes in activation energy but also by a decrease of the preexponential factor. The alloy‐induced decrease in the preexponential factor is associated with removal of the degeneracy of the number of equivalent diffusion paths. The dependences obtained describe well experimentally observed changes in the diffusion coefficient of interstitial oxygen atoms and in the formation rate of oxygen‐related thermal donors in Si1‐xGex alloys. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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