Abstract
The ac conductivity of scandium-oxide thin films in the audio-frequency range at temperatures between 4 and 295 K has been measured. The frequency-dependent component of the conductivity was found to obey an equation of the form , where is the circular frequency and is a temperature-dependent quantity whose value is close to, but less than, unity. Interpretation of the results in terms of a single-phonon hopping theory does not yield satisfactory agreement. To account for the data a new hopping model is proposed. The conductivity is calculated for classical hopping of carriers between localization sites over potential barriers with a height distribution caused by the random spatial distribution of these sites. This model yields the behavior at high frequencies with the quantity () increasing almost linearly with temperature. In addition, it is predicted that a thermally activated dielectric-loss peak should occur for very low frequencies. It is suggested that this model may find broad application in the interpretation of ac conductivity results in amorphous materials.
- Received 28 January 1972
DOI:https://doi.org/10.1103/PhysRevB.6.1572
©1972 American Physical Society