The electrical conductivity of a‐Si:H films is measured in the frequency range of 100 to 6 × 106 Hz and in the temperature range 300 to 450 K. Loss peaks are detected, whose amplitude is affected by the Staebler‐Wronski effect, being enhanced by exposure to light and reduced by thermal annealing. The observed behaviour is dibed in terms of the superposition of two mechanisms of ac conduction: the loss peaks can be described in terms of a Simple Pair Hopping model, superimposed to a wideband behaviour described by the Correlated Barrier Hopping model.
The current‐voltage (I–U) characteristics, both under illumination from the photosensitivity region and the dark I–U characteristics, are studied in MeBi2O3Me structures at different temperatures versus sample thickness and the configuration and material of electrodes. In the I–U characteristics four distinct regions are observed: ohmic I ∼ U, superlinear I ∼ Un > 1, the region of reverse bend where the degree of nonlinearity decreases and approximates the value of n = 1, and the second superlinear region I ∼ Un > 1. With increasing temperature of the samples the degree of nonlinearity decreases, the voltage in the beginning of the superlinear region increases slightly. In MeBi2O3Me structures the nonlinear I–U characteristics are explained in terms of a semiconductor model with intergrain barriers. The height of intergrain barriers (φ0 = (0.19 to 0.24) eV) and the average size of crystallites (h = (0.25 to 0.35) μm) for δ‐Bi2O3 films are determined from the experimental I–U characteristics.
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