Journal
SURFACE SCIENCE
Volume 605, Issue 15-16, Pages 1381-1387Publisher
ELSEVIER
DOI: 10.1016/j.susc.2011.04.035
Keywords
LaAlO3/SrTiO3 interface; Cation intermixing
Categories
Funding
- Office of Science, Division of Materials Sciences and Engineering, U.S. Department of Energy
- Office of Biological and Environmental Research of the Department of Energy and located at Pacific Northwest National Laboratory
- Royal Society
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Interfacial intermixing and electronic structure were investigated at thin (3-5 unit cells.), epitaxial La-1 _ xAl1+xO3/SrTiO3(001) heterojunctions for x = 0 and +/- 0.05. Angle-resolved X-ray photoelectron spectroscopy reveals rather extensive cation intermixing for all films, independent of composition. The valence band offset for the nominally stoichiometric (x =0) film is 0.16 +/- 0.10 eV, with the valence band maximum of SrTiO3 being deeper in binding energy than that of LaAlO3. Similar values are obtained for x = +/- 0.05. There is no measurable band bending in either the LaAlO3 or the SrTiO3 near the interface. These results are at odds with first principles theoretical predictions based on perfect stoichiometry and an abrupt interface model. However, inclusion of intermixing in the compositional description of the interface results in successful prediction of the valence band offset and absence of band bending. 2011 Published by Elsevier B.V.
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