Temperature dependence of the electrical conductivity and thermoelectric power in MoTe2 single crystals

Thermoelectric power and dc electrical conductivity measurements are made on MoTe2 single crystals in a wide temperature range (77 to 770 K). The results are analyzed on the basis of impurity conduction. It is shown that three processes contribute to the total conductivity: Hopping conduction between impurity sites, scattering by optical modes, and, in the intrinsic domain, scattering by impurities. The thermal energy gap (0.99 eV) is approximately the same as the optical one (1.03 eV). The effective mass of electrons in the conduction band is not very different from the mass of the free electron (m* = 0.76 m), and the dielectric constant of the medium is K approximately 34. The agreement between theoretical and experimental results is quite good. A comparison with previous results performed on compact polycrystalline samples is given. (author)