Adsorption and decomposition of SiH4 on Pd(1 1 1)

SiH4 adsorption and decomposition on Pd(1 1 1) has been studied using high resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), and Auger electron spectroscopy (AES). SiH4 was found to adsorb dissociatively on Pd(1 1 1) at 150 K, resulting in SiHX species populating the Pd(1 1 1) surface. Spectroscopic data indicate that the primary SiHX species on the surface is SiH3, possibly mixed with smaller amounts of SiH2. HREELS data show the majority of surface SiHX species dissociate by approximately 250 K. TPD experiments show only H2 desorption; however, the kinetics of H2 desorption are clearly affected by SiH4 coverage. AES confirms the presence of Si on the Pd(1 1 1) surface above 250 K and shows complete diffusion of Si into the Pd bulk above 950 K. A slight broadening of the Si AES peak may indicate the presence of a Pd silicide above 500 K.