Local bonding structures of SiO films on H-terminated Si 100/ 2 surfaces studied by using high-resolution electron energy loss spectroscopy

We have investigated the relaxation in the structure of Si–O–Si bonds and the bonding states at high temperatures of Si–H and Si–D after the oxidation of H- and D-terminated Si 100.surfaces by using high-resolution electron energy loss spectroscopy HREELS.. The results of H D.desorption from SiO2 formed on H D.-terminated Si surfaces indicate that the Si–H D.bonds of 2O–Si–2H 2D.species are stable compared with those of O–Si–2H 2D.. A central-force-network model was used and it was found that the structural relaxation of Si–O–Si bonds on 2.7-monolayer ML.-thick SiO2 films becomes high with an increase in the annealing temperature. However, the force constant of thermal SiO2 grown at 7008C is higher than that of low-temperature SiO2 annealed at the same temperature. Moreover, the force constant is almost independent of the SiO2 thickness and the oxidation process above 2 ML. Consequently, the force constant is governed by the oxidation temperature. In addition, the Si–O–Si structure is hardly relaxed during annealing for 5 min when the thickness of SiO2 films is being increased. q1998 Elsevier Science B.V. All rights reserved