Gate-Variable Mid-Infrared Optical Transitions in a (Bi_(1−x)Sb_x)_2Te_3 Topological Insulator
Abstract
We report mid-infrared spectroscopy measurements of ultrathin, electrostatically gated (Bi_(1-x)Sb_x)_2Te_3 topological insulator films, in which we observe several percent modulation of transmittance and reflectance as gating shifts the Fermi level. Infrared transmittance measurements of gated films were enabled by use of an epitaxial lift-off method for large-area transfer of topological insulator films from infrared-absorbing SrTiO3 growth substrates to thermal oxidized silicon substrates. We combine these optical experiments with transport measurements and angle-resolved photoemission spectroscopy to identify the observed spectral modulation as a gate-driven transfer of spectral weight between both bulk and 2D topological surface channels and interband and intraband channels. We develop a model for the complex permittivity of gated (Bi_(1-x)Sb_x)_2Te_3, and find a good match to our experimental data. These results open the path for layered topological insulator materials as a new candidate for tunable, ultrathin infrared optics and highlight the possibility of switching topological optoelectronic phenomena between bulk and spin-polarized surface regimes.
Additional Information
© 2016 American Chemical Society. Publication Date (Web): December 12, 2016. The authors gratefully acknowledge support from the Department of Energy, Office of Science under Grant DE-FG02-07ER46405 and for facilities of the DOE "Light-Material Interactions in Energy Conversion" Energy Frontier Research Center (DE-SC0001293). W.S.W. also acknowledges support from an NDSEG Graduate Research Fellowship. A.R.D acknowledges fellowship support from the Resnick Institute and the Kavli Nanoscience Institute at Caltech. The authors are grateful to Prof. George Rossman for helpful discussions and use of his FTIR facilities. Author Contributions: W.S.W., V.W.B and H.A.A. conceived the ideas. Y.O. grew the films and W.S.W. fabricated the devices. W.S.W, Y.S. and Y.O. performed measurements. W.S.W and A.R.D calculated the optical model. All authors contributed to writing the paper. D.N.B, K.H., Q.K.X., and H.A.A. supervised the project. The authors declare no competing financial interests.Attached Files
Accepted Version - acs_2Enanolett_2E6b03992.pdf
Submitted - 1607.03844.pdf
Supplemental Material - nl6b03992_si_001.pdf
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Additional details
- Alternative title
- Gate-Variable Mid-Infrared Optical Transitions in a (Bi1-xSbx)2Te3 Topological Insulator
- Eprint ID
- 71381
- Resolver ID
- CaltechAUTHORS:20161024-104047478
- DE-FG02-07ER46405
- Department of Energy (DOE)
- DE-SC0001293
- Department of Energy (DOE)
- National Defense Science and Engineering Graduate (NDSEG) Fellowship
- Caltech
- Resnick Sustainability Institute
- Kavli Nanoscience Institute
- Created
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2016-10-24Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Resnick Sustainability Institute, Kavli Nanoscience Institute