Impact of Spin-Orbit Coupling on the Thermoelectric Properties of h-TaN Monolayer

This study investigates the structural, electronic, mechanical and thermoelectric properties of a two-dimensional h-TaN monolayer using first-principles density functional theory and Boltzmann transport theory. The electronic band structure shows a direct band gap of 0.61 eV without spin-orbit coupling (SOC), which becomes an indirect band gap of 0.39 eV with SOC. The mechanical analysis confirms that the h-TaN monolayer is elastically stable and isotropic, exhibiting a moderate Young’s modulus of 103.78 N/m and a Poisson’s ratio of 0.30, indicating a favorable balance between stiffness and exibility. Thermoelectric performance evaluated for n- and p-type doping at a fixed carrier concentration of 1 × 10 20 cm –3 over the temperature range of 250-700 K with or with-out SOC. With SOC, the p-type h-TaN monolayer demonstrates superior thermoelectric performance, achieving a maximum conversion efficiency of 8.81% at 700 K, compared to 5.93% for the n-type. The lattice thermal conductivity decreases significantly from 3.27 W/m·K at 300 K to 1.31 W/m·K at 700 K. These results highlight the dominant role of p-type carriers and establish h-TaN as a mechanically robust and promising candidate for nanoscale thermoelectric devices.