Electron beam doping in the damage-free region at room temperature was investigated before annealing. The impurity sheet was sandwiched between 2 semiconductor wafers, in a 3-layer specimen, and the outer surface was irradiated with 750keV or 7MeV electron beams. Interstitial displaced atoms in the overlayer, which were introduced by the irradiation, migrated to the semiconductor surfaces. These interstitials diffused rapidly at the surface, with a coefficient of the order of 10-5cm2/s. The diffusion process was observed by using atomic force microscopy. The impurity concentrations in the surface layer during irradiation were found to be of the order of the matrix atom concentration. Diffusion was enhanced by the kick-out mechanism at the specimen interface, and into the depth of the semiconductors.
Electron Beam Doping by Superdiffusion in Unirradiated Regions (X < 300Å) of Semiconductors at Room Temperature. T.Wada, H.Fujimoto, D.Toyota, H.Masuda, Y.Yamada, K.Mizusawa: Japanese Journal of Applied Physics - 1, 1997, 36[12B], 7669-80