Ml. Wise et al., H2O ADSORPTION-KINETICS ON SI(111)7X7 AND SI(111)7X7 MODIFIED BY LASER ANNEALING, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 13(4), 1995, pp. 1853-1860
Citations number
55
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
The adsorption kinetics of H2O on Si(111)7X7 and Si(111)7X7 modified b
y laser annealing were studied using laser-induced thermal desorption
and temperature-programmed desorption techniques at temperatures betwe
en 180 and 800 K. The laser-annealed Si(111)7X7 surface displayed an e
nhanced initial reactive sticking coefficient for H2O compared with th
e unmodified Si(111)7X7 surface. At 180 K, the initial reactive sticki
ng coefficient was S-0=6.9X10(-1) on laser-anmealed Si(111)7X7 compare
d with S-0=1.9X10(-2) on unmodified Si(111)7X7. This larger initial st
icking coefficient is attributed to the creation of a more reactive su
rface structure formed by the laser annealing process. At higher oxyge
n coverages, the reactivity of the laser-annealed surface changed and
displayed much slower H2O adsorption rates that were similar to the ki
netics on Si(111)7X7. The decreasing initial reactive sticking coeffic
ient versus increasing surface temperature suggested a precursor-media
ted adsorption mechanism on both the Si(111)7X7 and laser-annealed Si(
111)7X7 surfaces. After long H2O exposures, the oxygen coverage satura
ted at theta(0) approximate to 0.35 monolayers on Si(111)7X7 for tempe
ratures between 300 and 700 K. At higher surface temperatures, the sat
uration coverage increased prior to SiO desorption at temperatures abo
ve 900 K. This increase was attributed to the creation of additional d
angling bond adsorption sites following H-2 desorption at temperatures
above 700 K. (C) 1995 American Vacuum Society.