The effect of super-diffusion was examined in the non-irradiated region of 3 layer structures. Thus, GaAs substrates coated with vacuum-evaporated Si were doped with Si by electron-beam doping at 750keV using GaAs/Si//Si/GaAs systems. The samples were exposed to an electron beam to a fluence of 3.7 x 1017 to 5.0 x 1017/cm2, with a mean current density of 8.1A/cm2, in a Van de Graaff accelerator at 100C in a N2 gas atmosphere. The irradiated samples were studied using secondary-ion mass spectrometry and photoluminescence methods. This revealed the occurrence of super-diffusion. It was found that electron-beam doping occurred as a result of the interstitial migration of displaced interstitial atoms towards the Si//Si interface, strong surface diffusion at the interface and high impurity concentrations at the interface which induced concentration- and recombination-enhanced diffusion. Two kick-out mechanisms were identified for the substitution of migrating atoms in the GaAs substrate.

Superdiffusion of Impurity Atoms in Damage-Free Regions of Semiconductors. T.Wada, H.Fujimoto: Physica Status Solidi C, 2003, 0[2], 780-7