Hydrogen desorption kinetics from H-Si (111) surfaces studied by optical sum frequency generation and second harmonic generation

We have studied hydrogen desorption from a flat H‐Si (111)1 × 1 surface at 711 K by observing sum frequency generation (SFG) and second harmonic generation (SHG) spectra. Flat H‐Si (111) surfaces were prepared by dosing hydrogen molecules in an ultra‐high vacuum chamber with a base pressure of 〜10−8 Pa. Combining the SFG and SHG methods, the desorption order has been clarified over the whole hydrogen coverage range from 1 monolayer (ML) to 0 ML. The hydrogen desorption was assigned as second order in the high coverage range of 1 ML–0.18 ML by using SFG spectroscopy and as first order in the coverage range of 0.18 ML–0.0 ML by using SHG spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.