DIRECT-CURRENT ELECTRICAL-CONDUCTIVITY OF A GE-AU COMPOSITE THIN-FILMNEAR THE CRITICAL THRESHOLD

The Ge-Au polycrystalline film was prepared by room-temperature ageing and thermal annealing with amorphous film. A transmission electron mi croscopy investigation showed that the Au grains grow from a size of 1 0 nm in the unannealed sample to a size of 100 nm in the annealed samp le. The correlation length was calculated in order to give a descripti on of morphology geometry. The DC electrical resistance was measured o ver the temperature range of 77-300 K. Percolation theory was used to interpret the conductivity dependence on metal content, which can be e xpressed as sigma(m) = sigma(0)(x - x(c))(t), where x(c) is about 50.4 5% and t is about 1.34 for unannealed samples and 1.55 for annealed sa mples. The similar electrical conductance of the unannealed and anneal ed samples shows that the electrical conductivity is not sensitive to the growth of Au grains.