Electrical properties of thin copper sulfide films produced by the aggregation of nanoparticles formed in LB precursor

The present work is dedicated to the formation and characterization of copper sulfide layers. Nanoparticles of CuS were formed by exposing the deposited LB films of copper stearate to the H2S atmosphere for at least 12 It. The aggregation of the nanoparticles into thin layers was performed by washing the sample with chloroform after the reaction for removing stearic acid molecules. Electrical properties of CuS layers of different thickness were examined. The dependence of an electrical conductivity upon the frequency was observed. The electrical conductivity is strongly dependent upon the frequency when the thickness of the precursor copper stearate LB films is less than 30 bilayers. For such thickness the resultant aggregated layer is not continuous one and can be considered as a film of 'islands' separated one from the other. This fact is responsible for the increase of conductivity with frequency. Linear voltage-current characteristics with practically no dependence of the conductivity on frequency were measured for the films, obtained from more than 30 bilayers of the precursor. Typical resistivity of such layers was less than 1.0 Ohm cm. (C) 2002 Elsevier Science B.V. All rights reserved.