Enhanced thermoelectric properties of the Dirac semimetal Cd3As2

Abstract

We report an investigation of temperature- and doping-dependent thermoelectric behavior of the topological semimetal Cd₃As₂. The electrical conductivity, thermal conductivity, Seebeck coefficient, and figure of merit (ZT) are calculated using the Boltzmann transport theory. The calculated thermoelectric properties of the pristine Cd₃As₂ match well with the experimental results. Electron or hole doping, especially the latter, is found to much improve the thermoelectric behavior of the material. The optimum figure of merit ZT of Cd₃As₂ with electron doping is found to be about 0.5 at T = 700 K with n = 1 × 10²⁰ cm⁻³, which is much larger than the maximum experimental value obtained for pristine Cd₃As₂ (∼0.15). For p-type Cd₃As₂, the maximal value of the Seebeck coefficient as a function of temperature increases apparently with the increase of the hole doping concentration and its position shifts drastically towards the lower temperature region, compared to that of n-type Cd₃As₂. This leads to an optimum figure of merit ZT of about 0.5, obtained at a low temperature of 500 K (p = 1 × 10²⁰ cm⁻³) in the p-type Cd₃As₂.