First principle calculations of GeTe and Ge2TeSe monolayers: Structural, electronic and thermoelectric properties

Abstract We have presented the structural, electronic and thermoelectric properties of GeTe and Ge2TeSe monolayers using density functional theory. It has been observed that Ge2TeSe monolayer is a direct band gap semiconductor opposite to GeTe monolayer which is an indirect band gap semiconductor. The electronic band structure and density of states for both monolayers have been calculated. An attempt is made to calculate and compare the temperature-dependent transport coefficients of both monolayers using the Boltzmann semi-classical theory. The Seebeck coefficient, electrical conductivity, power factor, and electronic thermal conductivity for both monolayers have been compared for different doping concentrations at 300 K, 500 K, and 700 K. It is found that the power factor of p-type Ge2TeSe monolayer is larger than that of p-type GeTe monolayer below carrier concentration ~1012 cm−2 at any temperature.