Tuning thermoelectric efficiency of monolayer indium nitride by mechanical strain

Abstract

Tuning the thermoelectric efficiency of a material is a complicated task as it requires the control of interrelated parameters. In this respect, various methods have been suggested to enhance the figure of merit (ZT), including the utilization of low-dimensional systems. Motivated by the effect of strain on intrinsic properties of two-dimensional materials, we examine the thermoelectric response of monolayer indium nitride (h-InN) under low biaxial strain (±1%) by using ab initio methods together with solving Boltzmann transport equations for electrons and phonons. Our results indicate that among the critical parameters, while the Seebeck coefficient is not affected prominently, electrical conductivity can increase up to three times, and lattice thermal conductivity can decrease to half at −1% strain where valence band convergence is achieved. This results in significant enhancement of ZT, especially for p-type h-InN, and it reaches 0.50 with achievable carrier concentrations (∼1013 cm−2) at room temperature. Thermoelectric efficiency further increases with elevated temperatures and rises up to 1.32 at 700 K, where the system remains to be dynamically stable, suggesting h-InN as a promising material for high-temperature thermoelectric applications.