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Experimental results on the diffusion of Zn in GaAs which could not be satisfactorily explained in terms of a Frank–Turnbull mechanism involving vacancies can be understood with a ’’kick-out model’’ in which the equilibrium between interstitial and substitutional Zn is established via gallium interstitials.

Shallow (<0.2 μm) n+ layers in Si with high conductivity (<40 Ω/⧠) have been formed by high-dose (2×1016 cm−2) As implants. Experimental observations of As distributions and carrier concentrations are successfully simulated by a computer program which accounts for both the concentration dependent diffusion and As clustering effects. Reduction of electrical carriers in high-dose As implanted Si during moderate temperature (∼800 ° C) heat treatments is readily explained by the kinetics of As clustering. Physical limitations on the conductivity which can be achieved by thermally annealed As implants in Si are also discussed.

It is well known that high surface concentration phosphorus diffusion leads to deeply penetrating ‘‘tails’’ in its concentration profile. At 700 °C the tail diffusivity exceeds that of low concentration phosphorus by a factor of 1000. Less spectacular, but very significant tailing also affects boron, making the conventional models contained in commonly available process simulation programs quite inaccurate for high concentrations of boron. We show that the observed tailing can be accounted for by a model whose central assumption is the local equality of dopant and oppositely directed defect fluxes.

The dose (fluence) of 200-keV boron, phosphorous, and antimony ions required to produce a continuous amorphous layer in silicon is determined as a function of target temperature. EPR measurements are used to monitor the process which is also then related to annealing effectiveness. The continuous amorphous layer recrystallizes at 550°C, after which only the implanted ions within that layer are completely electrically active. Carrier concentration profiles indicate the position of the amorphous layer and allow an approximate determination of the distribution with depth of damage. At the low dose rates used, reasonable agreement with a simple model for the formation of amorphous silicon as a function of ion, temperature, and dose is obtained.