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

摘要

We have studied hydrogen desorption from a flat H-Si (111)1x1 surface at 711K 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 0ML. The hydrogen desorption was assigned as second order in the high coverage range of 1ML-0.18ML by using SFG spectroscopy and as first order in the coverage range of 0.18ML-0.0ML by using SHG spectroscopy. Copyright (c) 2016 John Wiley & Sons, Ltd.