Thermoelectric Transport Properties of Monolayer GaN Semiconductor
摘要
This study employs density functional theory, Boltzmann transport theory, and the Slack model to systematically investigate the thermoelectric properties of monolayer GaN across various temperatures. It reveals that monolayer GaN exhibits significant Seebeck coefficients and power factors, attributable to the energy band degeneracy and the unique electronic structure, particularly in p-type materials where power factors peak at 8 mWm−1K−2 at 300 K. The effect of temperature on each parameter was explored and it was found that the Seebeck coefficient increases and the conductivity decreases as the temperature increases, however, the power factor remains relatively constant, indicating that the variation in the ZT is predominantly governed by thermal conductivity. Computational analyses unveiled coupling between the optical and acoustic phonon branches, resulting in reduced thermal conductivity, with lattice thermal conductivity converging at 1.72 Wm−1K−1, at room temperature (300 K). Further, calculations reveal that temperature also affects thermal conductivity, with rising temperature, phonon scattering intensifies, reducing thermal conductivity and thereby boosting the ZT, which can reach up to 4.3 for p-type GaN at 1200 K. These findings underscore the exceptional thermoelectric performance of monolayer GaN, which has excellent potential for applications in waste heat recovery, and aerospace.