Optical second-harmonic investigations of the isothermal desorption of SiO from the Si(100) and Si(111) surfaces
|Reviews and Highlights||Quantum Science||Molecular and Soft-matter||Ultrafast Nano-optics and Nanophotonics||Mineralogy and Geochemistry|
The isothermal desorption of SiO from the Si(100) and Si(111) surfaces was investigated by means of optical second-harmonic generation (SHG). Due to the high adsorbate sensitivity of this method, desorption rates could be measured over a wide range from 10−1 to 10−6 ML s–1. From their temperature dependence between 780 and 1000 K, activation energies of EA=3.4±0.2 eV and EA=4.0±0.3 eV and pre-exponential factors of n0=1016±1 s–1 and n0=1020±1 s–1 for SiO desorption were obtained for Si(100) and Si(111), respectively. In the case of the Si(100) surface, a pronounced decrease of the first-order rate constants was observed upon increasing the initial coverage from 0.02 to 0.6 ML. The results are interpreted in terms of coverage-dependent oxygen-binding configurations, which influence the stability of the oxide layer.