Adsorption of methylsilane on copper surfaces

The adsorption of methylsilane on the (1 1 1), (1 1 0) and polycrystalline surfaces of copper is examined using vibrational electron energy loss spectroscopy, angle-resolved ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy. On all surfaces, low exposures of methylsilane below −140 °C yield chemisorbed CH3Si species, while undissociated methylsilane physisorbs at higher exposures. This physisorbed layer then dissociates at higher temperatures to leave CH3Si on the surface by room temperature. Above room temperature, the VEELS and ARUP spectra suggest that Si–C bond cleavage occurs on the (1 1 1) surface, whereas the C–H bonds break to leave an SiC molecular species on the (1 1 0) surface. A surface–molecule bonding model is constructed to describe the adsorbate–substrate interactions and suggests that CH3Si adsorbs in a hollow site on the (1 1 1) surface and in a long-bridge site on the (1 1 0) surface.