The temperature-programmed desorption of D was used to probe pathways for H desorption from (001) surfaces. Experiments were performed on Ge-adsorbed Si(001), Si-adsorbed Ge(001) and SiGe(001) layers on Si(001). Deposition was carried out under ultra-high vacuum, using Si2H6 and Ge2H6 gaseous precursors. Following partial monolayer or alloy film growth, and sometimes post-deposition annealing, the samples were quenched to below 200C. The temperature-programmed desorption peaks were fitted by using Polanyi-Wigner models. Both the Si and the Ge monodeuteride desorption energies were found to decrease linearly with increasing Ge coverage. A comparison of adsorbed-layer and alloy-film results also showed that D desorption energies depended not only upon the surface-layer Ge coverage, but also upon the second-layer Ge concentration as well. It was shown that H desorption from Si sites occurred directly, rather than via diffusion to, and subsequent desorption from, lower-binding energy Ge sites.

Pathways for Hydrogen Desorption from Si1-xGex(001) during Gas-Source Molecular-Beam Epitaxy and Ultra-High Vacuum Chemical Vapor Deposition H.Kim, P.Desjardins, J.R.Abelson, J.E.Greene: Physical Review B, 1998, 58[8], 4803-8