Influence of biaxial strain on the electronic and thermoelectric properties of Sb2Te3 monolayer

We investigate the influence of biaxial strain on the electronic and thermoelectric properties of Sb2Te3 monolayer by first-principles calculation and semiclassical Boltzmann transport theory. The calculated results of formation energy and phonon spectrum suggest there is a limited strain for Sb2Te3 monolayer. The effective mass of hole increases with the increase of tensile strain, but decreases with the increase of compressive strain. However, the change trend of electron effective mass with strain is opposite to that of hole effective mass. The results of energy band structures show that the Sb2Te3 monolayer is an indirect energy gap semiconductor. Three conduction band valleys almost degenerate together at 5% compressive strain. At this strain, Seebeck coefficient and power factor are improved for n-type doped Sb2Te3 monolayer, suggesting that strain engineering is an effective way to improve the thermoelectric properties of Sb2Te3 monolayer.