X-ray photoelectron spectroscopy has been used to measure the valence band offset (VBO) of the w-InN/h-BN heterojunction. We find that it is a type-II heterojunction with the VBO being −0.30 ± 0.09 eV and the corresponding conduction band offset (CBO) being 4.99 ± 0.09 eV. The accurate determination of VBO and CBO is important for designing the w-InN/h-BN-based electronic devices.

The titanium nitride thin film was successfully prepared via direct nitridation of the sol–gel derived TiO2 thin film at different temperatures in ammonia gas. The composition, microstructure and optical properties of the thin films were characterized in order to investigate their effect on the surface‐enhanced Raman scattering (SERS) performance of the thin films. With the nitridation temperatures increasing, the anatase phase transformed into titanium nitride phase in the films and the concentration of nitrogen incorporation increased accordingly. Consequentially, the sol–gel derived TiO2 thin film was converted to non‐stoichiometry titanium nitride (TiOxNy) thin film, as determined by X‐ray diffraction (XRD), RAMAN and X‐ray photoelectron spectroscopy (XPS). As a result, a blue‐shift of the surface plasmon resonance absorption peaks and narrowing optical band gap of the thin films were observed, leading to the improvement of SERS performance via electromagnetic enhancement mechanism and charge‐transfer effect. In addition, the surface of thin films became gradually rough with the nitridation temperatures increasing, ascribed to the growth of titanium nitride crystal grains. Most of all, the thin films nitrided at 1000 °C had the most rough surface, and many ‘hot spots’ formed on the thin film surface accordingly, which were favorable for enhancing SERS‐active, and thereby the thin films exhibited the largest SERS enhancement. Copyright © 2017 John Wiley & Sons, Ltd.

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The valence band offset (VBO) of the wurtzite ZnO∕4H-SiC heterojunction is directly determined to be 1.61±0.23eV by x-ray photoelectron spectroscopy. The conduction band offset is deduced to be 1.50±0.23eV from the known VBO value, which indicates a type-II band alignment for this heterojunction. The experimental VBO value is confirmed and in good agreement with the calculated value based on the transitive property of heterojunctions between ZnO, SiC, and GaN.

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MgO may be a promising gate dielectric and surface passivation film for InN based devices and the valence band offset of MgO∕InN heterojunction has been measured by x-ray photoelectron spectroscopy. The valence band offset is determined to be 1.59±0.23eV. Given the experimental band gap of 7.83 for the MgO, a type-I heterojunction with a conduction band offset of 5.54±0.23eV is found. The accurate determination of the valence and conduction band offsets is important for use of MgO∕InN electronic devices.

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