Thermoelectric performance of silicene under uniform biaxial strain: A first principles study

Abstract Whenever a material is grown on a substrate, an external strain is induced on the material due to the lattice mismatch between the substrate and the material. Strain engineering plays an important role in tuning the electronic, vibrational and mechanical properties of a material by proper choice of lattice mismatch. We investigate the effect of biaxial strain on thermoelectric transport coefficients in low-buckled monolayer silicene using first principles study. The compressive strain shows the lattice instability while tensile strain shows stability with a small band-gap opening at the K-point. We systematically estimate the temperature dependent average relaxation time by calculating the electron-phonon coupling in silicene. Incorporation of the relaxation time in transport coefficients along with the effect of external strain increases the practicality of our investigations. The doped behaviour of silicene is also predicted using the rigid-band approximation. We find that with the applied tensile strain, the Seebeck coefficient and electronic thermal conductivity improves while the electrical conductivity and lattice thermal conductivity degrades slightly from its relaxed value.