The mechanism of B migration in the amorphous Si network was clarified. The B diffusivity in a-Si was much higher than that in crystalline Si; it was transient and increased with B concentration up to 2 x 1020B/cm3. At higher densities, B atoms in a-Si quickly precipitated. The B diffusion was indirect, mediated by dangling bonds present in a-Si. The density of dangling bonds was enhanced by B accommodation in the a-Si network and decreased because of a-Si relaxation. Accurate data simulations permitted the extraction of the dangling bond diffusivity, whose activation energy was 2.6eV.

Mechanism of Boron Diffusion in Amorphous Silicon. S.Mirabella, D.De Salvador, E.Bruno, E.Napolitani, E.F.Pecora, S.Boninelli, F.Priolo: Physical Review Letters, 2008, 100[15], 155901