Using density-functional theory calculations, an interstitial-based fast B diffusion mechanism was identified in amorphous Si. It was found that interstitial-like point defects, omnipresent in as-implanted Si, was very stable in an amorphous network and could form a highly mobile pair with B atoms. The transient existence of such point defects in amorphous Si was suggested to play an important role in B diffusion. The activation energy for this pathway was found to be 2.73eV, in good agreement with experimental results. In addition, this mechanism was consistent with the experimentally reported transient and concentration-dependent features of B diffusion in amorphous Si.

Interstitial-Based Boron Diffusion Dynamics in Amorphous Silicon. N.Kong, T.A.Kirichenko, G.S.Hwang, S.K.Banerjee: Applied Physics Letters, 2008, 93[8], 082109