Role of hydrogen prepairing in the hydrogen desorption kinetics from Si(100)-2×1: effects of hydrogenating-gas and thermal history

Hydrogen desorption kinetics from Si(100)-2×1:H has been systematically investigated using temperature-programmed desorption (TPD) on several hydrogenating gases and thermal conditions. As a result, the desorption kinetic order with the hydrogen coverage was found to increase in the order: atomic hydrogen<disilane<silane and room-temperature adsorption<high-temperature adsorption<post-annealing. These variations in kinetic order, depicted as a TPD peak shift at low hydrogen coverages, are universally described with a single surface parameter, γ0, the fractional coverage of unpaired hydrogen atoms. Fitting with obtained TPD spectra demonstrates that γ0 is a delicate function of the hydrogenating gas and thermal history.