Predicted High Thermoelectric Performance of Quasi-Two-Dimensional Compound GeAs Using First-Principles Calculations

摘要

The electronic structure of binary quasi-two-dimensional GeAs is investigated using first-principles calculations,and it is found that the anisotropic structure of the layered compound GeAs brings about the anisotropy of the transport properties.Meanwhile,the band structure of GeAs exhibits a relatively large dispersion near the valence-band maximum in the Z-V direction while it is rather flat in the Z-F direction,which is highly desirable for good thermoelectric performance.The calculated partial charge density distribution also reveals that GeAs possesses anisotropic electrical conductivity.Based on the semi-classical Boltzmann transport theory,the anisotropic transport properties are observed,and the optimal doping concentrations are estimated.The temperature dependence transport properties of p-type GeAs are compared with the experimental data in good agreement,and the theoretical figure-of-merit ZT has been predicted as well.