Electrical switching in sol-gel derived Ag-SiO2 nanocomposite thin films -: art. no. 084302

The sol-gel technique has been used to produce Ag-SiO2 nanocomposite thin films consisting of silver nanoparticles embedded in a SiO2 matrix. The size of the silver nanoparticles is of about (4 +/- 0.2) nm when the firing temperature is in the (500-700 degrees C) range, as determined from ultraviolet-visible spectroscopy analysis. The increase of the firing temperature beyond 300 degrees C, was found to lead to an outer diffusion of Ag toward the surface. As a consequence the surface atomic concentration of Ag is found to increase from 1.3% to 12% for the as-dried (at 120 degrees C) and for those further fired at 600 degrees C, respectively. On the other hand, it is shown that the electrical behavior of these Ag-SiO2 nanocomposite films can drastically change from highly insulating to conducting depending on the firing temperature used. In the intermediate firing temperature (300-400 degrees C) range, the films were found to exhibit a reversible switching behavior with a resistivity transition of about 7 orders of magnitude between the insulating (OFF) and the conducting (ON) state. Such an electrical switching could be explained by a change in the predominant conduction mechanism of the films. (C) 2005 American Institute of Physics.