AC LOSS ORIGINATING FROM MESOSCOPIC AND MACROSCOPIC INHOMOGENEITIES IN HYDROGENATED AMORPHOUS-SILICON

A recent formulation of the classical frequency response of an inhomog eneous medium using a percolation path method has been applied to inte rpret the ac loss of a-Si:H films in which local conductivity variatio ns induced by inhomogeneities on a macroscopic and/or mesoscopic scale are expected to exist. In this model, the ac loss is closely related to the dc conductivity, sigma(0), and fitting the experimental data pr oduces a dielectric relaxation time, tau, which is in good agreement w ith the expected value, i.e., epsilon(infinity)/sigma((0) (where epsil on(infinity) is the background permittivity of the material) in both m agnitude and temperature dependence.