Thermopower and conductivity activation energies in hydrogenated amorphous silicon

The long range fluctuation model has been widely used to account for the difference in activation energies seen experimentally in dark conductivity and thermopower measurements in hydrogenated amorphous silicon. We report on a test of this model using measurements of the conductivity and thermoelectric effects carried out in both open and short circuit configurations. While the thermopower activation energy is less than that of the dark conductivity, the short circuit Seebeck conductivity is found to be nearly identical to the dark conductivity in both activation energy and magnitude, consistent with the long range fluctuation model.