Journal of Vacuum Science & Technology A, Vol.14, No.3, 1822-1825, 1996
Atomic-Hydrogen Adsorption on Si(100)-(2X1) with Preadsorbed Acetylene - Structure, Bonding, and Chemical-Reactions
The adsorption of atomic hydrogen on acetylene-saturated Si(100)-(2x1) was studied using high-resolution electron energy loss spectroscopy, temperature programmed desorption, Auger electron spectroscopy, and low-energy electron diffraction (LEED). With saturation coverage of preadsorbed acetylene, the initial adsorption probability of atomic hydrogen on Si is reduced to 40% of the initial adsorption probability of atomic hydrogen on clean Si(100)-(2x1), and the uptake of hydrogen to form the Si monohydride up to 0.65+/-0.05 of a monolayer is observed. Although the hydrogenation of acetylene is substantially slower than the chemisorption of hydrogen as the Si monohydride, molecular desorption of ethylene is observed in temperature programmed desorption following the hydrogenation of chemisorbed acetylene. With further postexposures of atomic hydrogen, the LEED pattern changes from (2x1) to (1x1) and the Si dihydride forms, confirming the conversion of ethylene to ethyl.