Electrostatic modulation of thermoelectric transport properties of 2H-MoTe2

Tianhui Zhu; Sree Sourav Das; Safoura Nayeb Sadeghi; Farjana Ferdous Tonni; Sergiy Krylyuk; Costel Constantin; Keivan Esfarjani; Albert V. Davydov; Mona Zebarjadi

doi:10.1039/D3YA00316G

Electrostatic modulation of thermoelectric transport properties of 2H-MoTe₂†

Tianhui Zhu,

‡^a Sree Sourav Das,^a Safoura Nayeb Sadeghi,

^b Farjana Ferdous Tonni,^a Sergiy Krylyuk,^c Costel Constantin,^d Keivan Esfarjani,^bef Albert V. Davydov^c and Mona Zebarjadi

*^ae

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* Corresponding authors

^a Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia, USA
E-mail: m.zebarjadi@virginia.edu

^b Department of Mechanical and Aerospace Engineering, University of Virginia Charlottesville, Virginia, USA

^c Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA

^d Department of Physics and Astronomy, James Madison University, Harrisonburg, Virginia, USA

^e Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia, USA

^f Department of Physics, University of Virginia, Charlottesville, Virginia, USA

Abstract

Two-dimensional layered transition metal dichalcogenides are potential thermoelectric candidates with application in on-chip integrated nanoscale cooling and power generation. Here, we report a comprehensive experimental and theoretical study on the in-plane thermoelectric transport properties of thin 2H-MoTe₂ flakes prepared in field-effect transistor geometry to enable electrostatic gating and modulation of the electronic properties. The thermoelectric power factor is enhanced by up to 45% using electrostatic modulation. The in-plane thermal conductivity of 9.8 ± 3.7 W m⁻¹ K⁻¹ is measured using the heat diffusion imaging method in a 25 nm thick flake. First-principles calculations are used to obtain the electronic band structure, phonon band dispersion, and electron–phonon scattering rates. The experimental electronic properties are in agreement with theoretical results obtained within energy-dependent relaxation time approximation. The thermal conductivity is evaluated using both the relaxation time approximation and the full iterative solution to the phonon Boltzmann transport equation. This study establishes a framework to quantitively compare first-principle-based calculations with experiments in 2D layered materials.

This article is part of the themed collection: SDG 7: Affordable and clean energy

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Electrostatic modulation of thermoelectric transport properties of 2H-MoTe₂†

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