Direct current electrical conductivity of a Ge - Au composite thin film near the critical threshold

Abstract

The Ge - Au polycrystalline film was prepared by room-temperature ageing and thermal annealing with amorphous film. A transmission electron microscopy investigation showed that the Au grains grow from a size of 10 nm in the unannealed sample to a size of 100 nm in the annealed sample. The correlation length was calculated in order to give a description of morphology geometry. The DC electrical resistance was measured over the temperature range of 77 - 300 K. Percolation theory was used to interpret the conductivity dependence on metal content, which can be expressed as , where is about 50.45% and t is about 1.34 for unannealed samples and 1.55 for annealed samples. The similar electrical conductance of the unannealed and annealed samples shows that the electrical conductivity is not sensitive to the growth of Au grains.