Low-temperature thermopower in quasiamorphous carbons

Results are presented from a study of the thermopower of quasiamorphous carbons in the temperature interval from 20 to 200 K. It is shown that the thermopower of quasiamorphous carbons is described satisfactorily in a model based on the series connection of regions with metallic conductivity, hopping conductivity with a variable hopping length, and hopping conductivity with a constant hopping length. It is found that when considering the thermopower of the regions with the metallic conductivity, it is necessary to take into account the temperature dependence of the main mechanisms of carrier scattering. The parameters of the electronic structure of quasiamorphous carbon are calculated using experimental data on the temperature dependence of the electrical resistivity and thermopower. (C) 2000 American Institute of Physics. [S1063-777X(00)00701-5].