Electrical conduction and photoluminescence properties of solution-grown ZnO nanowires

We report on the optical and electrical properties of zinc oxide nanorods synthesized in solution using Oswald ripening of ZnO nanodots with the addition of ethylenediamene growth directing agent. This method results in high quality, single crystalline ZnO nanorods that extend up to 3 mu m in length and have an average diameter of 25 +/- 7 nm, compared to similar to 75 nm diameter for similarly prepared nanorods but without the addition of the growth directing agent. Furthermore, we find that the higher aspect ratio nanorods exhibit strong size-dependent electrical characteristics, with a critical diameter of about 27 nm delimiting nonconductive and conductive behaviors. Theoretical calculations indicate that the origin of this size-dependent conductivity is the presence of surface states that deplete the carriers in the smaller diameter nanorods, and an estimate of the density of these states is provided. (c) 2007 American Institute of Physics.