Desorption activation energy of hydrogen from the Si (111)1x1: H surface studied by optical sum frequency generation and second harmonic generation

Abstract

The desorption kinetics of hydrogen from the H-Si (111)1 × 1 surface prepared by molecular hydrogen exposure has been studied by combining optical sum frequency generation (SFG) for higher coverage and second harmonic generation (SHG) for lower coverage at several sample temperatures from 711 K to 770 K. The hydrogen desorption activation energy was found as Ed = 60.1 ± 8.8 kcal/mol (2.60 ± 0.38 eV) for the second order desorption for the coverage above 0.44 ML. For the first order desorption at the coverage below 0.18 ML the desorption activation energy was found as Ed= 32.6 ± 8.1 kcal/mol (1.41±0.35 eV).