Transfer of hydrogen atoms and site exchange between Ge and Si atoms during germane adsorption at Si (001)

Germane (GeH₄) adsorption at Si(001) at room temperature has been investigated through observations of surface hydrides by means of temperature-programmed desorption and multiple-internal-reflection Fourier-transformed infrared spectroscopy. For surfaces with considerable concentration of dimer vacancies, prepared by in-situ thermal cleaning followed by rapid cooling, saturation with germane presented almost full coverage of SiH without any Ge or Si-higher hydrides, which strongly suggests site exchange between ad-Ge and substrate Si atoms. For a smoother surface prepared by forming a Si epilayer, the Ge dihydride is much populated at higher doses of germane. From measurements using (1 × 2) single domain surface and polarized lights in FTIR, the Ge dihydrides are found to be at their "in-dimer" position rather than the "intra-row" position.