Wu Xuming, Gao Guoying, Hu Lei, Qin Dan
School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
Physics Department, Binzhou Medical University, 264003 Yantai, Shandong, People's Republic of China.
Nanotechnology. 2021 Mar 26;32(24). doi: 10.1088/1361-6528/abedeb.
Recently, the experimentally synthesized NbSiTewas found to be a stable layered narrow-gap semiconductor, and the fabricated field-effect transistors (FETs) based on few-layers NbSiTeare good candidates for ambipolar devices and mid-infrared detection (Zhao201910705-10). 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 NbXTe(X = Si, Ge) and the gate voltage effect on the thermoelectric performance of the FET based on monolayer NbSiTe. It is found that both monolayers have large-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 NbSiTe(NbGeTe). The gate voltage can effectively increase the thermoelectric performance for the NbSiTe-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 NbXTemonolayers are promising candidates for 2D thermoelectric materials and thermoelectric devices.
最近，实验合成的NbSiTe被发现是一种稳定的层状窄带隙半导体，基于少层NbSiTe制造的场效应晶体管（FET）是双极器件和中红外探测的良好候选材料（Zhao 201910705 - 10）。在此，我们使用第一性原理结合玻尔兹曼输运理论和非平衡格林函数方法，研究单层NbXTe（X = Si，Ge）的热电输运系数以及栅极电压对基于单层NbSiTe的FET热电性能的影响。研究发现，由于“布丁模类型”的价带结构，这两种单层材料都具有大类型的塞贝克系数，并且它们都表现出各向异性的热电行为，对于NbSiTe（NbGeTe），在300 K时的最佳热电优值为1.4（2.2），在500 K时为2.8（2.5）。栅极电压可以有效地提高基于NbSiTe的FET的热电性能。在负栅极电压下，高热电优值可以在很宽的温度范围内保持。此外，该FET表现出良好的栅极可调塞贝克二极管效应。目前的工作表明，NbXTe单层是二维热电材料和热电器件的有前途的候选材料。
