The co-diffusion of As and B which had been implanted to doses of about 1016/cm2, using energies which gave the same projected range, was investigated at 900 and 1000C by measuring dopant and carrier profiles. A comparison of co-diffusion data, with the results which were obtained by the separate diffusion of each element, revealed anomalous effects which could be explained by positing the formation of neutral donor-acceptor pairs. These complexes were mobile, with diffusivities that could be described by:

D (cm2/s) = 1.7 x 101exp[-4(eV)/kT]

Such values were very close to the diffusivity of As in intrinsic Si. On the basis of the results, a diffusion model was proposed which took pairing into account. A simulation which included this model permitted the prediction of the anomalous phenomena that occurred during the high-concentration co-diffusion of donors and acceptors. The agreement with observed profiles was generally good.

Codiffusion of Arsenic and Boron Implanted in Silicon. S.Solmi, S.Valmorri, R.Canteri: Journal of Applied Physics, 1995, 77[6], 2400-6