Precipitation of antimony delta-doping layers in Si studied with channeling Rutherford backscattering spectrometry

Antimony 5-doping layers in Si have been prepared using molecular beam epitaxy. First of all, a crystalline buffer layer was deposited at 700°C, followed by Sb deposition from a Knudsen cell. After cooling down to room temperature, amorphous Si was deposited on top and subsequently crystallized using solid phase epitaxy (SPE). The thermal stability of the 8-doping layers was studied in the temperature range of 625-725°C which is only slightly above the SPE temperature. Lateral Sb redistribution was followed by measurement of the Sb minimum yield in channeling Rutherford backscattering spectrometry. An increase in minimum yield was found and was correlated with the formation of precipitates as measured with transmission electron microscopy. The high diffusion coefficients required to explain the observed precipitation are qualitatively in agreement with a diffusion model, based on percolation theory, proposed before for Sb diffusion in heavily doped Si