Decomposition of Si H3 to Si H2 on Si(100)- (2x1)

Abstract

The decomposition energetics of the silyl group into silylene and hydrogen on the Si(100)- (2x1) surface was studied using pseudopotential density functional calculations. The results provided insight on the relative stability of the adsorption configurations of silylene in the presence of different coverages of coadsorbed hydrogen. We find that the prevalence of the intrarow silylene on the growth surface is a result of both thermodynamics and kinetics. Our results also suggest that both the silylene group and the hydrogen atom formed by silyl decomposition acquire frustrated translational energy in the exit valley of the decomposition pathway. In particular, the hydrogen atom is approximately 0.5 eV more energetic than the thermal energy. This is consistent with observations made in scanning tunnel microscope images that show the dissociating hydrogen atom migrating away from the decomposition site. © 2006 The American Physical Society.