The Activated Adsorption of Silane on Nickel

The dissociative adsorption of silane (SiH sub 4) on Ni(100) was studied using Auger electron spectroscopy, thermal desorption mass spectroscopy, high resolution electron energy loss spectroscopy, and low-energy electron diffraction. The effects of varying the surface temperature (100- 1200K), the gas temperature (300-600K), and deuteration (SiD sub 4 vs. SiH sub 4) were examined. Adsorption occurs through an extrinsic precursor state with the reactive sticking coefficient (S sub r) increasing approximately linearly with increasing surface temperature. Raising the gas temperature is also effective at increasing S sub r. We find no significant change in S sub r when SiD sub 4 is adsorbed indicating that motion of the central silicon atom is most likely involved in the transition state. At surface temperatures less than 250K the stable species is a silyl (SiH sub 3) group. The dissociation of this species, the formation of Ni sub 2 Si thin films, and the dissolution of silicon into bulk nickel are also discussed. Our results are compared to recent studies on the adsorption of CH sub 4 on nickel and silane on silicon.