A channeled ion energy loss study of the surfactant-mediated growth of Ge on Si(100)

Scattered ion energy distribution for the system Sb/Ge/Si(100) are studied using transmission ion channeling. One monolayer (ML) of Sb was deposited on the clean Si(100) surface prior to deposition of one ML of Ge at 350 degrees C. Experimental energy distributions for the [100], {110}, and ''random'' directions are compared with simulated energy distributions obtained by overlapping trial adsorbate positions (relative to bulk positions) with ion positions in the channel at the beam-exit surface. Ion positions and energies are calculated via a Monte Carlo simulation of channeling that incorporates a model for channeled ion energy loss. We find that the energy distributions clearly show that the surfactant, Sb, moves to the surface upon Ge deposition at 350 degrees C. Further, our results are consistent with the sites recently reported by Grant et al. [Surf. Sci. 316 (1994) L1088], for Sb deposited on Ge/Si(100), namely, tilted Sb dimers on Ge asymmetrically displaced from bulk sites.