Diode junctions between two ZnO nanoparticles: mechanism of rectification

Abstract

We form junctions between two ZnO nanoparticles. Such junctions are formed by electrostatic adsorption of two different monolayers in sequence. While one of the monolayers contains intrinsically n-type ZnO nanoparticles, concentration of Al dopant in the other monolayer is varied. All the junctions show current rectification. In one of the several control experiments, direction of rectification in a junction reverses when sequence of the components in the junction is inversed. This rules out any effect of interface or metal electrode in the observed current rectification. We study the mechanism of rectification that occurs in such a narrow junction. From the current-voltage characteristics, we evaluate the ideality factor of the diodes and find that a recombination current predominates in these junctions in the voltage range of our studies. Capacitance-voltage measurements show that a depletion layer has indeed formed between the two nanoparticles.