Three-pairs of doublet bands assigned to SiH<inf>2</inf> scissoring modes observed in H<inf>2</inf>O-induced oxidation of Si(100) surfaces

Oxidation of Si(100) surfaces by H2O has been investigated on 2H+H2O/Si(100)−(2×1), H2O+Si(100)−(2×1), as well as H2O+H/Si(100)−(2×1) systems by infrared reflection absorption spectroscopy using CoSi2 buried metal layer substrates (BML-IRRAS). Three pairs of doublet bands assigned to the scissoring modes of adjacent and isolated SiH2 with zero, one, and two inserted back-bond oxygen atoms, respectively, have been reported. This report also has clearly shown the unique high sensitivity of BML-IRRAS for the perpendicular components in the fingerprint region, compared to the multiple internal reflection and the external transmission arrangements. Oxidation mechanisms have been proposed. In the 2H+H2O/Si(100) −(2×1) system, oxygen insertion into the back bond occurs easily. In the H2O+H/Si(100) system, however, the tunneling effect is important to reach the oxygen inserted state. © 2004 The American Physical Society.