Two-junction-nanowire arrays (SnO 2 capped ZnO nanowire arrays on Zn substrate) are synthesized using a two-step-solution-reaction. The bare single crystalline ZnO nanowires give reasonably intense band edge luminescence but also strong green emission likely due to surface defects. The SnO 2 capping treatment not only introduces caps on the tip of the ZnO nanowires but also partially passivates the nanowire surfaces, leading to improved near band edge emission and the suppression of the defect luminescence. The nanowire array configuration allows a straight forward electrical measurement on the single nanowire junction (Zn−ZnO−SnO 2 ). The I−V results indicate that a little barrier exists in between the Zn substrate and the nanowire. The observation of more complicated electrical behaviors of the two-junction system (Zn/ZnO/SnO 2 ) discloses the nonuniform doping of the SnO 2 cap, which is consistent with the EDX compositional analysis.

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Indium tin oxide nanowires have been grown by dc sputtering on different substrates without the use of catalysts or oblique deposition. The nanowire length was of the order of several µm, while their diameter was ∼50-100 nm. Small side branches on the nanowires were frequently observed. The nanowires were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The growth mechanism of the nanowires is discussed.

Treatment of ZnO nanowires (NWs) using hydrogen peroxide with increasing concentration results in a continuous increase in the amount of -OH group at the surfaces of the NWs, which demonstrates different characteristics in the transport behaviors of the NWs. Combined with results from theoretical simulation and microphotoluminescence, the variation in the nanowire transport property is explained by the change of carrier density and mobility as induced by the surface treatment.