Direct Measurement of Density-of-States Effective Mass and Scattering Parameter in Transparent Conducting Oxides Using Second-Order Transport Phenomena

The Boltzmann transport equation can be solved to give analytical solutions to the resistivity, Hall, Seebeck, and Nernst coefficients. These solutions may be solved simultaneously to give the density-of-states (DOS) effective mass, the Fermi energy relative to either the conduction or valence band, and a scattering parameter that is related to a relaxation time and the Fermi energy. The Nernstcoefficient is essential for determining the scattering parameter and, thereby, the effective scattering mechanism(s). We constructed equipment to measure these four transport coefficients simultaneously over a temperature range of 30-350 K for thin, semiconducting films deposited on insulating substrates.