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The platinum/[niobium-doped strontium titanate] junction (Pt/SrTiO3:Nb) was investigated by x-ray photoemission (XPE) spectroscopy. Aluminum Kα and synchrotron radiation (6 keV) were used to obtain XPE spectra with different probing depths. The broadening and shift of the XPE peaks for SrTiO3:Nb, which resulted from the formation of a potential barrier at the interface, were quantitatively analyzed by fitting simulations. The barrier height was calculated to be 0.7-0.8 regardless of the Nb concentration. Furthermore, the XPE profile of the junction was reproduced when the permittivity of SrTiO3 was assumed to depend on the electric field. [ABSTRACT FROM AUTHOR]

The polar surfaces of wurtzite-type zinc oxide (ZnO) were characterized by x-ray photoemission spectroscopy to identify the origin of the polarity dependence of the valence band spectra. A characteristic sub-peak always appeared in the valence band spectra of the (0001) face regardless of the surface preparation conditions. It also appeared in the valence band spectra of the (10[formula]2) face, but only when the photoelectron take-off angle was parallel to the c-axis of ZnO. Our analysis demonstrates that this take-off angle dependency originates not from the surface state, photoelectron diffraction, or the presence of surfactants but from the crystal polarity. [ABSTRACT FROM AUTHOR]

This work reports on the detection of the valence band of buried Heusler compounds by means of hard x-ray photoemission spectroscopy. The measurements have been performed on the so-called “half” tunnel junctions that are thin films of Co2MnSi underneath MgO. Starting from the substrate, the structure of the samples is MgO(buffer)–Co2MnSi–MgO(tMgO)–AlOx with a thickness tMgO of the upper MgO layer of 2 and 20 nm. The valence band x-ray photoemission spectra have been excited by hard x rays of about 6 keV energy. The valence band spectra have been used to estimate the mean free path of the electrons through the MgO layer to be 17 nm at kinetic energies of about 6 keV. In particular, it is shown that the buried Co2MnSi films exhibit the same valence density of states as in bulk samples. [ABSTRACT FROM AUTHOR]

A correction to the article "Determination of Schottky barrier profile at Pt/SrTiO3:Nb junction by x-ray photoemission," by Naoki Ohashi and colleagues that was published in the December 20, 2012 issue is presented.

Abstract: We report on the electronic structure of three different types of N-containing carbon-based cathode catalysts for polymer electrolyte fuel cells observed by hard X-ray photoemission spectroscopy. Prepared samples are derived from: (1) melamine and poly(furfuryl alcohol), (2) nitrogen-doped carbon black and (3) cobalt phthalocyanine and phenolic resin. C 1s spectra show the importance of sp 2 carbon network formation for the oxygen reduction reaction (ORR) activity. N 1s spectra of the carbon-based cathode catalysts are decomposed into four components identified as pyridine-like, pyrrole- or cyanide-like, graphite-like, and oxide nitrogen. Samples having high oxygen reduction reaction activity in terms of oxygen reduction potential contain high concentration of graphite-like nitrogen. O 1s spectra are similar among carbon-based cathode catalysts of different oxygen reduction reaction activity. There is no correlation between the ORR activity and oxygen content. Based on a quantitative analysis of our results, the oxygen reduction reaction activity of the carbon-based cathode catalysts will be improved by increasing concentration of graphite-like nitrogen in a developed sp 2 carbon network. [ABSTRACT FROM AUTHOR]