Formation and decomposition of Si hydrides during adsorption of Si₂H₆ onto Si(100) (2 × 1)

Infrared absorption spectroscopy in the multiple internal reflection geometry and hybrid density-functional cluster calculation are used to characterize the adsorption structure of hydride species that form during adsorption of disilane on Si(100)(2 × 1) at room temperature. We suggest that disilane dissociatively adsorbs without breaking its Si-Si bond to produce an adatom dimer, -H₂Si-SiH₂-, that bridges two adjacent dimers. We demonstrate that at low hydride coverage, a trihydride (-SiH₃) formed by breaking the Si-Si bond of Si₂H₆, decomposes into dihydride and monohydrides, while at high hydride coverage, the trihydride decomposition is quenched. We also suggest that the impinging rate of adsorbing molecules has a significant effect on the adsorption kinetics.