Diodelike behavior in glass–metal nanocomposites

One-dimensional arrays of nanoparticles of silver and copper, respectively, have been grown within a silicate glass by an electrodeposition process. Silver–silica nanocomposites were prepared using a melt quenched glass whereas sol–gel derived glass was used for the synthesis of copper–silica nanocomposites. The metal particle diameters had values ranging from 1.5 to 20 nm. The composite structures exhibited a diodelike current–voltage characteristic in the temperature range 300 to 160 K for silver containing nanocomposites and at around 280 K for copper containing nanocomposites. The diode action is believed to be caused by the presence of metal–semiconductor nanojunctions in these glass—the typical number of such junctions being 60. The rather narrow range of temperature for diode action as observed in copper–silica nanocomposites is ascribed to the easy breakup of the metal nanoarrays because of the sol–gel derived medium of silica glass in which the metal phase was grown. The metal particles of diameter ∼2 nm constituted the semiconducting phase in these nanojunctions.