Potential Energy Landscape Of An Interstitial O_2 Molecule In A Sio_2 Film Near The Sio_2/si(001) Interface

摘要

Potential energy distribution of interstitial O_2 molecule in the vicinity of SiO_2/Si(001) interface is investigated by means of classical molecular simulation. A 4-nm-thick SiO_2 film model is built by oxidizing a Si(001) substrate, and the potential energy of an O_2 molecule is calculated at Cartesian grid points with an interval of 0.05 nm in the SiO_2 film region. The result shows that the potential energy of the interstitial site gradually rises with approaching the interface. The potential gradient is localized in the region within about 1 nm from the interface, which coincides with the experimental thickness of the interfacial strained layer. The potential energy is increased by about 0.62 eV at the SiO_2/Si interface. The result agrees with a recently proposed kinetic model for dry oxidation of silicon [Phys. Rev. Lett. 96, 196102 (2006)], which argues that the oxidation rate is fully limited by the oxidant diffusion.