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arXiv · 2110.10799

Band Structure and Polarization Effects in Photothermoelectric Spectroscopy of a Bi2Se3 Device

Seyyedesadaf Pournia·Giriraj Jnawali·Ryan F. Need·Howard E. Jackson·Stephen D. Wilson·Leigh M. Smith
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Abstract

Bi2Se3 is a prototypical topological insulator which has a small band gap (~0.3 eV) and topologically protected conducting surface states. This material exhibits quite strong thermoelectric effects. Here we show in a mechanically exfoliated thick (~100 nm) nanoflake device that we can measure the energy dependent optical absorption through the photothermoelectric effect. Spectral signatures are seen for a number of optical transitions between the valence and conduction bands, including a broad peak at 1.5 eV which is likely dominated by bulk band-to-band optical transitions but is at the same energy as the well known optical transition between the two topologically protected conducting surface states. We also observe a surprising linear polarization dependence in the response of the device that reflects the influence of the metal contacts.

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Seyyedesadaf Pournia, Giriraj Jnawali, Ryan F. Need, Howard E. Jackson, Stephen D. Wilson, Leigh M. Smith. 2021-10-20. Band Structure and Polarization Effects in Photothermoelectric Spectroscopy of a Bi2Se3 Device. https://doi.org/10.1063/5.0075924

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