Vibrational studies of CH 3I on Si(100)-(2×1): adsorption and decomposition of the methyl species

Abstract

The dissociative adsorption of CH 3I to adsorbed CH 3 and I on a clean Si(100)-(2×1) surface has been studied by high resolution electron energy loss spectroscopy (HREELS), temperature-programmed desorption (TPD) and Auger electron spectroscopy. The thermal stability of CH 3(a) to 600 K has been witnessed spectroscopically. At higher temperatures, CH 3(a) decomposes to CH(a), possibly via the production of intermediate CH 2(a) species. The CH(a) species is stable to ≈800 K. HREELS and TPD show that following CH 3I dissociative adsorption at 100 K, a multilayer of undissociated CH 3I is condensed on the substrate. Upon heating, this condensed overlayer is desorbed with a peak temperature of 225 K. H 2 and I desorption occur near 785 K, leaving adsorbed carbon on the Si(100) surface.