Abstract
A series of [(SnSe)1+δ]m[TiSe2]2 heterostructure thin films built up from repeating units of m bilayers of SnSe and two layers of TiSe2 were synthesized from designed precursors. The electronic structure of the films was investigated using X-ray photoelectron spectroscopy for samples with m = 1, 2, 3, and 7 and compared to binary samples of TiSe2 and SnSe. The observed binding energies of core levels and valence bands of the heterostructures are largely independent of m. For the SnSe layers, we can observe a rigid band shift in the heterostructures compared to the binary, which can be explained by electron transfer from SnSe to TiSe2. The electronic structure of the TiSe2 layers shows a more complicated behavior, as a small shift can be observed in the valence band and Se3d spectra, but the Ti2p core level remains at a constant energy. Complementary UV photoemission spectroscopy measurements confirm a charge transfer mechanism where the SnSe layers donate electrons into empty Ti3d states at the Fermi energy.
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Acknowledgments
This material is based upon the work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. 1309047. The authors acknowledge the support from the National Science Foundation under grant DMR-1710214. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
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Göhler, F., Hamann, D.M., Rösch, N. et al. Electronic structure of designed [(SnSe)1+δ]m[TiSe2]2 heterostructure thin films with tunable layering sequence. Journal of Materials Research 34, 1965–1975 (2019). https://doi.org/10.1557/jmr.2019.128
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DOI: https://doi.org/10.1557/jmr.2019.128