Abstract
Single-layer graphene (SLG) sheets can exhibit thermoelectric properties under the control of gate voltage. The controlled factors and regulation mechanism of SLG thermoelectric properties have become research hotspots. In this paper, a SLG thermoelectric parameter model considering carrier concentration and mobility with temperature and gate voltage is proposed. Based on the proposed model, the square resistance ( $R_{\mathrm {s}}$ ) and Seebeck coefficient ( $S$ ) of the SLG are calculated. The results show that the maximum value of $R_{\mathrm {s}}$ decreases from 5.8 $\text{K}\Omega $ to 3.2 $\text{K}\Omega $ at the Dirac voltage when the temperature increases from 100 K to 500 K. A large and stable $S$ can be obtained at high voltages and temperatures. The maximum value of $S$ can reach $161.3~\mu \text{V}$ /K at $T = 500$ K, exhibiting a more obvious thermoelectric characteristic. Simultaneously, the saturation law of the power factor ( $Q$ ) with the change of gate voltage and the amplitude regulation of $Q$ by temperature are obtained. This work can provide a theoretical basis for analyzing the thermoelectric characteristics of SLG.
Highlights
The thermoelectric effect is the direct conversion of heat into electricity or electricity into heat and includes the Seebeck effect, the Peltier effect and the Thomson effect [1]
The carrier concentration, mobility and the thermoelectric parameters of Single-layer graphene (SLG) are combined through the two variables T and VG0
The square resistance, the Seebeck coefficient, the power factor and the Seebeck voltage of SLG are calculated, and the mechanism of these thermoelectric parameters under different conditions is analyzed in detail
Summary
The thermoelectric effect is the direct conversion of heat into electricity or electricity into heat and includes the Seebeck effect, the Peltier effect and the Thomson effect [1]. Its Seebeck coefficient is very low due to the zero band gap of ideal graphene [15], which makes graphene unsuitable as a thermoelectric material. Experiments have confirmed that the carrier mobility of graphene changes with the generation of its band gap [19] This scale regulation is difficult to use flexibly after fabrication. The carrier concentration and mobility of SLG, including the thermoelectric parameters, are regulated by the temperature and gate voltage. A model of the SLG thermoelectric parameters that considers the carrier concentration and mobility at various temperatures and gate voltages is proposed. The carrier concentration in the SLG can be regulated by the vertical electric field applied by the back gate voltage (VG). The variations of the carrier concentration and the mobility in the SLG are studied, and the square resistance of the SLG is calculated to investigate the electrical properties of SLG under an electric field
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