VIBRATIONAL STUDIES OF CH3I ON SI(100)-(2X1) - ADSORPTION AND DECOMPOSITION OF THE METHYL SPECIES

The dissociative adsorption of CH3I to adsorbed CH3 and I on a clean Si(100)-(2 x 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 CH3(a) to 600 K has been witnessed spectroscopically. At higher temperatures, CH3(a) decomposes to CH(a), possibly via the production of intermediate = CH2(a) species. The CH(a) species is stable to almost-equal-to 800 K. HREELS and TPD show that following CH3I dissociative adsorption at 100 K, a multilayer of undissociated CH3I 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.