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Photoemission techniques have been used to discern the nature of the species involved in the adsorption of germane and catalytically decomposed germane on a Si(111)7\ifmmode\times\else\texttimes\fi{}7 surface. It has been shown that the catalytic decomposition of germane induces--at very low substrate temperature (RT--300 \ifmmode^\circ\else\textdegree\fi{}C)--in the Ge adsorption process, a mechanism quite different from the undecomposed germane adsorption. In this study, GeH, ${\mathrm{GeH}}_{2}$, and ${\mathrm{GeH}}_{3}$ radicals have been experimentally identified.

We present an in situ study of low-pressure hydrogen, silane, and disilane chemisorption on Si(111) surfaces. Only characteristic signatures of mono and dihydride phases are evidenced. At room temperature sticking of ${\mathrm{SiH}}_{2}$ or (${\mathrm{SiH}}_{2}$${)}_{\mathrm{n}}$ species for ${\mathrm{SiH}}_{4}$ and ${\mathrm{Si}}_{2}$${\mathrm{H}}_{6}$, respectively, are proposed and related to the back bonds of the dimer\char21{}adatom\char21{}stacking-fault model.