The effect of Sb surfactant on the growth of (GenSim)p layers on Si(0 0 1): a reflEXAFS study

The effect of Sb in the growth of Ge/Si systems was studied by the total reflection extended X-ray absorption fine structure technique at the Ge K-edge. (GenSi10−n)15 multilayers (n=2 and 4) were grown on Si(0 0 1) substrate kept at 550 °C with and without a predeposition of 1 ML of Sb. From the analysis of the experimental data the surfactant effect was quantified in terms of Ge–Si interdiffusion. The intermixing appeared to be appreciably reduced by the Sb action for the (Ge2Si8)15 multilayers, while for (Ge4Si6)15 samples the reduced interdiffusion effect due to Sb was not detected. In any case the Ge–Ge and the Ge–Si first neighbors bond lengths was found to be close to the sum of their costituent-element atomic radii. Finally, we found that the deposition of a submonolayer of Sb is not enough to completely prevent from interdiffusion even in case of 2 Ge monolayers buried in silicon and grown on a Si(0 0 1) substrate at 400 °C.