Silicene: an excellent material for flexible electronics

Abstract

The outstanding properties of graphene have laid the foundation for exploring graphene-like two-dimensional systems, commonly referred to as 2D-Xenes. Amongst them, silicene is a front-runner owing to its compatibility with current silicon fabrication technologies. Recent works on silicene have unveiled its useful electronic and mechanical properties. The rapid miniaturization of silicon devices and the useful electro-mechanical properties of silicene necessitates the exploration for potential applications of silicene flexible electronics in the nano electro-mechanical systems. Using a theoretical model derived from the integration of ab-initio density-functional theory and quantum transport theory, we investigate the piezoresistance effect of silicene in the nanoscale regime. Like graphene, we obtain a small value of piezoresistance gauge factor of silicene, which is sinusoidally dependent on the transport angle. The small gauge factor of silicene is attributed to its robust Dirac cone and strain-independent valley degeneracy. Based on the obtained results, we propose to use silicene as an interconnect in flexible electronic devices and a reference piezoresistor in strain sensors. This work will hence pave the way for exploring flexible electronics applications in other 2D-Xene materials.

Density Functional Theory of Straintronics Using the Monolayer-Xene Platform: A Comparative Study

“…Figure (i),(iii), and (v) depicts that conductance increases with an increase in energy and strain due to an increase in the number of TMs passing through the Dirac cone in AC strain. The increase in TMs is related to the deformation of the Dirac cone from a circle to an ellipsoid . For the ZZ strain, the plots will exhibit opposite characteristics due to the oval shape of the Dirac cone.…”

“…where t is the thickness of the material and L and W represent the two-dimensional length and width of the material, respectively. For silicene, by taking its thickness to be 0.313 nm 37 and the corresponding values of length, width, and Poisson ratio from, 50 the critical strain obtained is around 8%. Moreover, there is a Dirac material-to-metal transition for a uniaxial tensile strain of 7.5% for silicene.…”

“…For germanene and stanene, a 1 × 1 rectangular supercell consisting of 4 atoms is constructed to study the effect of uniaxial strain on their electronic structures. Further calculation details are given in our previous work on silicene …”

“…We compute the Slater–Koster (SK) parameter, V ppπ , by fitting the DFT band structure to a TB model using TB-Studio . The relation between the SK parameter of strained and pristine Xenes is provided in ref . The magnitude of hopping amplitude for pristine silicene, germanene, and stanene is 1.03, 0.99, and 0.76 eV, respectively.…”

“…Further calculation details are given in our previous work on silicene. 50 The strain range for different Xenes is chosen considering their e l and i l , as listed in Table 1. Quantitative support of this critical strain is based on the continuum mechanics model, 51 which is given as follows ( )…”