Zirconium Lα radiation has been utilized to investigate the chemical bonding in silicon compounds by x-ray photoelectron spectroscopy. The compounds studied in the present investigation are SiO2, SiO, SiC, Si3N4, and silicon-oxynitrides. The spectra in the Si 1s and KLL Auger regions were recorded for these compounds and compared with the elemental spectra. In order to estimate the change in chemical environment of Si in these compounds, the Auger parameter was determined in each case as the difference between the binding energies for the 1s and the KLL peaks. The trend in the value of the Auger parameter is correlated with the degree of atomic relaxation due to the increasing neutralization of charge around the Si cations in these compounds. A good agreement was found between the change in the Auger parameter and the bond ionicity calculated for the Si cation in these compounds. Using this plot, the bond ionicities were determined for the oxynitrides. A model is also developed to estimate these ionicities from the concentrations of oxygen and nitrogen present in these compounds. The values of the ionicities obtained by these two different methods give a satisfactory agreement. We have shown that the plot between the change in the Auger parameter and the bond ionicity could be used to estimate the bond ionicities.

Thin films of cobalt (about 20 nm) were deposited on a silicon ⟨100⟩ substrate. The deposition was carried out using the e-beam technique. The films were oxidized under two different conditions: in vacuum and in a quartz tube furnace. The elemental cobalt and the two oxidized samples were characterized by the technique of x-ray photoelectron spectroscopy. Magnesium Kα radiation (1253.6 eV) was used as the source of the x-ray excitation. The spectral data in the cobalt 2p, 2s, 3s, 3p, Auger LMM regions, oxygen 1s region, and carbon 1s regions were recorded under a high resolution mode. The sample oxidized in vacuum showed features distinct from that oxidized in the quartz tube furnace. The data will serve as a comparison for the cobalt oxides formed under different processing conditions.

The Ti/SnO₂ interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO₂ substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO₂ and the titanium overlayer at the interface. The SnO₂ was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO₂ to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO₂, elemental titanium, TiO₂, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO₂ upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

The interfacial reactivity at the Co/CuO interfaces has been investigated in situ by the technique of x-ray photoelectron spectroscopy. Thin films of cobalt were evaporated on the CuO substrates by the technique of e-beam. The depositions were undertaken by maintaining the substrates at ambient temperature. Significant differences have been observed in the Cu 2p core level spectra recorded for these samples and that for pure CuO. The Co 2p core level spectrum also shows differences upon comparison with the spectrum for elemental cobalt. These differences arise from chemical interaction occurring at the Co/CuO interface. The curve fitting technique has been utilized to estimate the relative percentages of the constituents at the interface. The interface width has been determined from the relative percentage of the unoxidized cobalt present in the overlayer. The dependence of the interface width has also been explored as a function of annealing temperature. The interface width is much less for the room temperature deposited sample as compared to that for annealed samples. The spectral data also indicate increase in the diffusion of copper oxide through the cobalt overlayer with increasing temperature.