Variable-depth excitation, achieved by using various electron injection energies, provided a clear distinction between luminescence which was derived from the near-interface region of the oxide film, from the Si/oxide interface 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. The 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. The effect of hydrogenation at 400C, rapid thermal annealing at 900C, and especially their combination, was to reduce markedly the intensities of the cathodoluminescence features which were due to interfacial and sub-oxide bonding defects.

Depth-dependent spectroscopic defect characterization of the interface between plasma-deposited SiO2 and silicon J.Schäfer, A.P.Young, L.J.Brillson, H.Niimi, G.Lucovsky: Applied Physics Letters, 1998, 73[6], 791-3