Band alignment of epitaxial SrTiO3 thin films with (LaAlO3)0.3-(Sr2AlTaO6)0.7 (001)

Abstract

SrTiO${}_3$ (STO) epitaxial thin films and heterostructures are of considerable interest due to the wide range of functionalities they exhibit. The alloy perovskite (LaAlO${}_3$)${}_{0.3}$-(Sr${}_2$AlTaO${}_6$)${}_{0.7}$ (LSAT) is commonly used as a substrate for these material structures due to its structural compatibility with STO and the strain-induced ferroelectric response in STO films grown on LSAT. However, surprisingly little is known about the electronic properties of the STO/LSAT interface despite its potentially important role in affecting the overall electronic structure of system. We examine the band alignment of STO/LSAT heterostructures using x-ray photoelectron spectroscopy for epitaxial STO films deposited using two different molecular beam epitaxy approaches. We find that the valence band offset ranges from +0.2(1) eV to -0.2(1) eV depending on the film surface termination. From these results we extract a conduction band offset from -2.4(1) eV to -2.8(1) eV, indicating that the conduction band edge is more deeply bound in STO and that LSAT will not act as a sink or trap for electrons in the supported film or multilayer.

14 pages, 3 figures; Accepted in Applied Physics Letters

References in corpus (2)

• Surface Reconstructions in Molecular Beam Epitaxy of SrTiO3
• Visible light carrier generation in co-doped epitaxial titanate films

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