ZnO nanorods were synthesized by a simple aqueous solution method. Crystal structures and morphology studies show that the ZnO nanorods are single crystalline with the growth direction aligned with the c axis of ZnO. An Au-ZnO nanorod-Au (metal-semiconductor-metal, MSM) device using the synthesized nanorod was fabricated. An electronic model with two back-to-back Schottky diodes in series with a nanorod was used to describe the electrical transport of the MSM device. A positive temperature coefficient of resistance is observed on a single ZnO nanorod from 383 to 473 K. A simple model has been proposed to explain such an abnormal behavior including the effect of the interface states and the adsorption-desorption of the water/oxygen molecules on the surface of the nanorod.
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