Thermoelectric properties of highly-mismatched alloys of GaNxAs1−x from first- to second-principles methods: energy conversion

Abstract

The transport properties of GaN_xAs_1−x (x = 0.0, 0.25, 0.5, 0.75 and 1.0) alloys are investigated using the semi-classical Boltzmann theory as implemented in the BoltzTraP code. The electronic structures are calculated using the full potential linearized augmented plane wave method within the recently modified Becke-Johnson potential to solve the exchange correlation potential. These alloys possess a direct band gap varying between 0.5 and 3.2 eV. The ‘special quasi-random structures’ approach of Zunger was used to reproduce the randomness of the GaN_xAs_1−x alloys for the first few shells around a given site. The carrier concentration (n), electrical conductivity (σ/τ), Seebeck coefficient (S), electronic thermal conductivity (κ_e/τ) and the electronic power factor (S²σ/τ), as a function of temperature were obtained for GaN_xAs_1−x alloys. In addition, the transport properties as a function of chemical potential at three constant temperatures were investigated. It has been found that GaN_xAs_1−x alloys show good transport properties, therefore, we expect that these alloys could be possible potential candidates for clean energy applications.