Electrical characterisation of LB films containing US nanoparticles

CdS nanoparticles were formed within LB films of either Cd salts of stearic acid (SA) or calix[8]arene (CA) by exposing the samples to H2S gas. A series of DC and AC electrical measurements were performed for both planar and sandwich structures over a wide range of frequencies. Exponential behaviour of the DC I-V characteristics of the sandwich structures is typical for electron tunnelling through multilayered LB films. The conductivity value decreases after formation of CdS nanoparticles in the film, which is believed to be caused by the reduced layer-by-layer film order. AC measurements show a traditional insulating behaviour for all kind of films studied. Formation of CdS clusters in the LB films resulted in the decrease in both the capacitance and AC conductivity, which can be interpreted by the drop in the polarisability in disordered LB films. (C) 2002 Elsevier Science B.V. All rights reserved.