Cation mixing, band offsets and electric fields at LaAlO3/SrTiO3(001) heterojunctions with variable La:Al atom ratio

Journal Article · Mon Aug 01 00:00:00 EDT 2011 · Surface Science

DOI:https://doi.org/10.1016/j.susc.2011.04.035· OSTI ID:1025667

Qiao, L.; Droubay, T. C.; Kaspar, T. C.; Sushko, P. V.; Chambers, S. A.

Interfacial intermixing and electronic structure were investigated at thin (3–5 unit cells.), epitaxial La_1-xAl_1+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. Finally, 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.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1025667
• Report Number(s): PNNL-SA-80121; 42315; KC0203020; TRN: US201120%%678
• Journal Information: Surface Science, Vol. 605, Issue 15-16; ISSN 0039-6028
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
BENDING
BINDING ENERGY
CATIONS
ELECTRIC FIELDS
ELECTRONIC STRUCTURE
FORECASTING
HETEROJUNCTIONS
STOICHIOMETRY
VALENCE
X-RAY PHOTOELECTRON SPECTROSCOPY
band offset
band bending
intermixing
electric fields
Environmental Molecular Sciences Laboratory