The out-diffusion of implanted Be was found to be identical after capless or capped (nitride or oxide) rapid thermal annealing at temperatures of 900 to 1000C. It depended upon the Be dose and its proximity to the surface. Out-diffusion was more pronounced when the Be implant was shallow (less than 100nm) and/or the Be+ dose was high (greater than 1015/cm2). It was demonstrated that Be out-diffusion was driven by the presence of a highly damaged surface layer. Auger results indicated the formation of a BeOx compound at the surface of a high-dose (1016/cm2) Be-implanted sample that was subjected to capless rapid thermal annealing (1000C, 1s). It appeared that BeOx formation occurred when the out-diffused Be interacted with native Ga/As oxides during annealing. All of the Be which remained in the GaAs, after rapid thermal annealing at temperatures above 900C for 2s, was electrically active.

H.Baratte, D.K.Sadana, J.P.De Souza, P.E.Hallali, R.G.Schad, M.Norcott, F.Cardone: Journal of Applied Physics, 1990, 67[10], 6589-91