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Gate-Variable Mid-Infrared Optical Transitions in a (Bi_(1−x)Sb_x)_2Te_3 Topological Insulator

Whitney, William S. and Brar, Victor Watson and Ou, Yunbo and Shao, Yinming and Davoyan, Artur R. and Basov, D. N. and He, Ke and Xue, Qi-Kun and Atwater, Harry A. (2017) Gate-Variable Mid-Infrared Optical Transitions in a (Bi_(1−x)Sb_x)_2Te_3 Topological Insulator. Nano Letters, 17 (1). pp. 255-260. ISSN 1530-6984. doi:10.1021/acs.nanolett.6b03992.

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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.

Item Type:Article
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URLURL TypeDescription Information Paper
Whitney, William S.0000-0001-5269-2967
Davoyan, Artur R.0000-0002-4662-1158
Atwater, Harry A.0000-0001-9435-0201
Alternate Title:Gate-Variable Mid-Infrared Optical Transitions in a (Bi1-xSbx)2Te3 Topological Insulator
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.
Group:Resnick Sustainability Institute, Kavli Nanoscience Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG02-07ER46405
Department of Energy (DOE)DE-SC0001293
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
Resnick Sustainability InstituteUNSPECIFIED
Kavli Nanoscience InstituteUNSPECIFIED
Subject Keywords:Bismuth antimony telluride, topological insulator, tunable optical properties, mid-infrared, Burstein−Moss shift, optical modulator
Issue or Number:1
Record Number:CaltechAUTHORS:20161024-104047478
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Official Citation:Gate-Variable Mid-Infrared Optical Transitions in a (Bi1–xSbx)2Te3 Topological Insulator William S. Whitney, Victor W. Brar, Yunbo Ou, Yinming Shao, Artur R. Davoyan, D. N. Basov, Ke He, Qi-Kun Xue, and Harry A. Atwater Nano Letters 2017 17 (1), 255-260 DOI: 10.1021/acs.nanolett.6b03992
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71381
Deposited By: Tony Diaz
Deposited On:24 Oct 2016 17:56
Last Modified:11 Nov 2021 04:44

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