We have elucidated the mechanism for B migration in the amorphous (a-) Si network. B diffusivity in a-Si is much higher than in crystalline Si; it is transient and increases with B concentration up to 2 x 1020 B/cm3. At higher density, B atoms in a-Si quickly precipitate. B diffusion is indirect, mediated by dangling bonds (DB) present in a-Si. The density of DB is enhanced by B accommodation in the a-Si network and decreases because of a-Si relaxation. Accurate data simulations allow one to extract the DB diffusivity, whose activation energy is 2.6 eV. Implications of these results are discussed.
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Mechanism of boron diffusion in amorphous silicon
S. Mirabella, D. De Salvador, E. Bruno, E. Napolitani, E. Pecora, S. Boninelli, F. Priolo
Physical Review Letters, 100, 155901 (2008) -
B clustering in amorphous Si
D. De Salvador, G. Bisognin, M. Di Marino, E. Napolitani, A. Carnera, S. Mirabella, E. Pecora, E. Bruno, F. Priolo, H. Graoui, M. A. Foad, F. Boscherini
The Journal of Vacuum Science and Technology B 26, 382 (2008) -
Experimental investigations of boron diffusion mechanisms in crystalline and amorphous silicon
D. De Salvador, E. Napolitani, S. Mirabella, E. Bruno, G. Impellizzeri, G. Bisognin, E. F. Pecora, F. Priolo, A. Carnera
Materials Science and Engineering B, 154-155, 240 (2008)