Electronic, Thermal, and Thermoelectric Transport Properties of ε-Ga₂O₃ from First Principles

The electronic, thermal, and thermoelectric transport properties of ε-Ga₂O₃ have been obtained from first-principles calculation. The band structure and electron effective mass tensor of ε-Ga₂O₃ were investigated by density functional theory. The Born effective charge and dielectric tensor were calculated by density perturbation functional theory. The thermal properties, including the heat capacity, thermal expansion coefficient, bulk modulus, and mode Grüneisen parameters, were obtained using the finite displacement method together with the quasi-harmonic approximation. The results for the relationship between the Seebeck coefficient and the temperature and carrier concentration of ε-Ga₂O₃ are presented according to the ab initio band energies and maximally localized Wannier function. When the carrier concentration of ε-Ga₂O₃ increases, the electrical conductivity increases but the Seebeck coefficient decreases. However, the figure of merit of thermoelectric application can still increase with the carrier concentration.