Current fluctuations and switching effects in hydrogenated amorphous silicon/molybdenum multilayer thin films

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Abstract
Current-voltage characteristics and the temperature-dependent conductivity have been investigated for multilayer samples consisting of nanometre-size Mo clusters arranged in planes, which are separated by hydrogenated amorphous Si sublayers 80 nm thick. The samples show unique electronic properties which are reported for the first time. A typical electric field of 80 Vcm−1 applied to the samples with a coplanar electrode configuration results in a switching from a semiconducting to a metallic state with typical conductivities at room temperature of 10−6 and 1Ω−1 cm−1, respectively. The switching effect, which is reversible by thermal annealing at 450 K, is accompanied by chaotic current fluctuations with a ratio of maximum to minimum current of typically a factor of three and in some cases up to three orders of magnitude. The temperature dependence of the conductivity in. the metallic state is described by σ = σ0exp(-T 0/T)½ with typically σ0 = 3 Ω−1 cm−1 and T 0 = 240 K.