Abstract
Abstract
Recently, the experimentally synthesized Nb2SiTe4 was found to be a stable layered narrow-gap semiconductor, and the fabricated field-effect transistors (FETs) based on few-layers Nb2SiTe4 are good candidates for ambipolar devices and mid-infrared detection (Zhao et al 2019 ACS Nano
13 10705–10). Here, we use first-principles combined with Boltzmann transport theory and non-equilibrium Green’s function method to investigate the thermoelectric transport coefficients of monolayer Nb2XTe4 (X = Si, Ge) and the gate voltage effect on the thermoelectric performance of the FET based on monolayer Nb2SiTe4. It is found that both monolayers have large p-type Seebeck coefficients due to the ‘pudding-mold-type’ valence band structure, and they both exhibit anisotropic thermoelectric behavior with optimal thermoelectric figure of merit of 1.4 (2.2) at 300 K and 2.8 (2.5) at 500 K for Nb2SiTe4 (Nb2GeTe4). The gate voltage can effectively increase the thermoelectric performance for the Nb2SiTe4-based FET. The high thermoelectric figure of merit can be maintained in a wide temperature range under a negative gate voltage. Furthermore, the FET exhibits a good gate-tunable Seebeck diode effect. The present work suggests that Nb2XTe4 monolayers are promising candidates for 2D thermoelectric materials and thermoelectric devices.
Funder
National Natural Science Foundation of China
Subject
Electrical and Electronic Engineering,Mechanical Engineering,Mechanics of Materials,General Materials Science,General Chemistry,Bioengineering
Cited by
9 articles.
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