Comparative study of elastic, thermodynamic properties and carrier mobility of InX (X = O, S, Se, Te) monolayers via first-principles

Abstract

With the generalized gradient approximation, our work presents a comparative research for elastic properties, carrier mobility and thermodynamic properties of InX (X = O, S, Se, Te) monolayers using first principles computational density functional theory (DFT). Among the four indium compounds of the same main group, they all show isotropic Young's modulus and Poisson's ratio. Among them, the Young's modulus and Poisson's ratio of InO are the largest, reaching 79.1 Nm−1 and 0.44, respectively. At the same time, we also calculated the cohesive energy of each primitive cell to explain their relationship. For the sake of studying the thermodynamic properties, the Helmholtz free energy in various area, area change, two-dimension bulk moduli, heat capacity of constant pressure and constant volume in different temperature are analyzing in detail. The heat capacity of both constant pressure and constant volume and thermal expansion coefficient adhere to the trend of InTe > InSe > InS > InO in the same temperature. Moreover, InO, InS and InSe have the negative thermal expansion coefficient at the low temperature. Furthermore, we used the deformation potential theory to calculate the carrier mobility, analyzing their elastic constants, deformation potential constants, and the effective mass of electrons and holes, and found that the effective mass of electrons is isotropic.