Laser-induced thermal desorption of Silicon-containing surface reaction intermediates from Si(111)7 × 7

Abstract

Laser-induced thermal desorption (LITD) was used to remove surface reaction intermediates from Si(111)7 × 7. Silicon-containing species were detected in the LITD yield from Si(111)7 × 7 surfaces covered with hydrogen, water or methanol. These silicon-containing LITD products include SiH n , Si(OH) n and Si(OCH 3) n where n = 1 − 3. None of these species were observed in the conventional temperature programmed desorption (TPD) spectra. TPD and temperature-pro-grammed LITD studies were also performed and correlated for Si(111)7 × 7 surfaces as a function of hydrogen coverage. The SiH 2 LITD products were related directly to the low-temperature β 2-peak in the H 2 TPD spectra. Previous infrared studies have demonstrated that this β 2-peak corresponds to H 2 desorption from silicon dihydride species on the silicon surface. The ability of LITD to desorb silicon-containing surface reaction intermediates should be extremely useful in investigations of silicon surface reaction kinetics.