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

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.