Transport properties and thermoelectric effects in gated silicene superlattices

Abstract

Low-dimensional thermoelectricity opens the possibility of improving the performance and the efficiency of thermoelectric devices by redistributing the electron density of states through the reduction of dimensionality. In this work, we explore this possibility in silicene by reducing its dimensionality through the periodic arrangement of gated electrodes, the so-called gated silicene superlattices. Silicene electrons were described quantum relativistically. The transmission, conductance, and thermoelectric properties were obtained with the transfer matrix method, the Landauer-Büttiker formalism, and the Cutler-Mott formula, respectively. We find that the redistribution of the density of states together with the intrinsic characteristics of silicene, the local bandgap and the large spin-orbit coupling, contribute to the enhancement of the thermoelectric properties. In particular, the Seebeck coefficient and the power factor reach values of a few mV/K and nW/K2. These findings in conjunction with the low thermal conductivity of silicene indicate that silicene-based nanostructures could be the basis of more efficient thermoelectric devices.

Thermoelectric effect and devices on IVA and VA Xenes

“…ZT of 4.9 was predicted in silicene by doping technology 179 . An external electrical field can be applied to tune the Seebeck coefficient, 180 up to a few mW K −1 , 181 and significantly decrease thermal conductivity, 182 suggesting viable thermoelectric performance in silicene. For stanene , most research centers on thermal conductivity simulation where results indicate thermal conductivity is insensitive to size effect due to its short intrinsic phonon MFPs 183 .…”

Enhancement of the thermoelectric properties in bilayer graphene structures induced by Fano resonances

“…In the case of thermoelectric properties, it is necessary to know the Seebeck coefficient, it can be done with the help of Cutler-Mott equation, 18,22,55,56…”

“…Finally, for a material to be a good thermoelectric, its power factor needs to be high. The power factor is defined by the squared magnitude of the Seebeck coefficient and the conductance, S 2 G. 18,22…”

“…12,13 Recent research in 2D materials such as graphene 1,2,14 and silicene [15][16][17] have reported values above 2 and even above the technological limit value ZT = 3. [18][19][20][21][22] Working with nanostructured 2D materials has become a trend, 18,[20][21][22][23][24][25] not only for its excellent properties, but also for the possible redistribution of the density of states. A high accumulation of states is linked to high values of ZT .…”

“…A high accumulation of states is linked to high values of ZT . 18,22,25 One of the materials that promises a lot to the technology industry is bilayer graphene. [26][27][28] This material is quasi-two-dimensional, with excellent electrical conductivity, 29 high thermal conductivity 30 and a modulable bandgap with the application of an external electric field.…”