The influence of defects on interfaces of semiconducting oxides

X-ray Photoelectron spectroscopy can be used to determine chemical and electronic interface properties. Chemical information obtained from this technique has a sensitivity limited to a few percent of a monolayer. In contrast,... [ view full abstract ]

X-ray Photoelectron spectroscopy can be used to determine chemical and electronic interface properties. Chemical information obtained from this technique has a sensitivity limited to a few percent of a monolayer. In contrast, electronic interface properties and their influence on device behavior are already affected by much lower concentrations of impurities and defects. The evaluation of XPS data regarding electronic properties does therefore significantly enhance the sensitivity and provide straightforward explanations for the variation of barrier heights and band alignment on interface preparation and treatment. Moreover, the measurements can reveal information about defect energies in the band gap, which can be compared to those obtained by other means. After an introduction to the scientific questions and experimental approach and the demonstration of some basic results, experiments on various semiconducting oxides, such as ZnO, SrTiO₃ and CeO₂ are presented.