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Articles you may be interested inDistinguishing the effect of surface passivation from the effect of size on the photonic and electronic behavior of porous siliconWe have investigated the influence of the microstructure and chemistry of the surrounding host on the strong visible photoluminescence ͑PL͒ from silicon nanoclusters ͑nc-Si͒ embedded in three different silicon-based dielectric compounds: Si x N y : H , Cl, Si x N y O z : H , Cl, and Si x O z :H,Cl, obtained from silicon nitride films deposited by SiH 2 Cl 2 /NH 3 /H 2 plasma-enhanced chemical vapor deposition at different growth pressures. A blueshift is found in the PL coming from the nc-Si as the content of oxygen in the surrounding host is increased, and a significant improvement in PL intensity is achieved when the nc-Si are well passivated with O instead of H. We discuss the PL behavior in terms of the quantum confinement model and passivation state of the nc-Si surface.

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In this work, relationships between chemical and physical properties of fluorine doped tin oxide films prepared by the chemical spray pyrolysis technique have been studied. Changes in the structural, optical and electrical properties of these films in relation to their doping concentrations determined by the resonant nuclear reaction analysis and x-ray photoelectron spectroscopy (XPS) techniques have been correlated. By XPS measurements, it was found that the fluorine content in the tin oxide films does not induce any chemical shift of the Sn and O core levels. At the same time, XPS measurements are carried out at low binding energy, shown that the valence band of heavy doped tin oxide changes with respect to that determined in SnO2 powder, due to the influence of the fluorine doping. In addition, it was shown that the formation of F–Sn complexes provides a decrease in both the concentration and mobility of the carriers.

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Polycrystalline samples of NbB 2+x with nominal composition (B/Nb) = 2.0, 2.1, 2.2, 2.3, 2.4 and 2.5 were studied by X-ray photoelectron spectroscopy (XPS). The spectra revealed Nb and B oxides on the surface of the samples, mainly B 2 O 3 and Nb 2 O 5 . After Ar ion etching the intensity of Nb and B oxides decreased. The Nb 3d 5/2 and B 1s core levels associated with the chemical states (B/Nb) were identified and they do not change with etching time. The Binding Energy of the Nb 3d 5/2 and B 1s core levels increase as boron content increases, suggesting a positive chemical shift in the core levels. On the other hand, analysis of Valence Band spectra showed that the contribution of the Nb 4d states slightly decreased while the contribution of the B 2p π states increased as the boron content increased. As a consequence, the electronic and superconducting properties were substantially modified, in good agreement with band-structure calculations.