Low-energy cathodoluminescence spectroscopy was used to study optical transitions at defect bonding arrangements in Si/SiO2 interfaces which had been prepared by means of low-temperature plasma deposition. Variable-depth excitation, obtained by using various electron injection energies, provided a clear distinction between luminescence from the near-interface region of the oxide film, from the Si/SiO2, and from the underlying crystalline Si substrate. Cathodoluminescence bands at about 0.8 and 1eV were attributed to interfacial Si atom dangling bonds with various numbers of back-bonded Si and O atoms. Cathodoluminescence spectroscopy also revealed higher photon-energy features. These included bands, at about 1.9 and 2.7eV, which were attributed to sub-oxide bonding defects in the as-grown oxide films. There was also a substrate-related feature at about 3.4eV. Hydrogenation at 400C, and/or rapid thermal annealing (900C), markedly reduced the intensities of cathodoluminescence spectroscopy features which were attributed to interfacial and sub-oxide bonding defects.

J.Schäfer, A.P.Young, L.J.Brillson, H.Niimi, G.Lucovsky: Applied Physics Letters, 1998, 73[6], 791-3