High-Performance UV Photodetection of Unique ZnO Nanowires from Zinc Carbonate Hydroxide Nanobelts

Abstract

Zinc carbonate hydroxide nanobelts are prepared by the hydrolysis of zinc acetate aqueous solution in the presence of urea at 90 °C. The zinc carbonate hydroxide nanobelts can be facilely self-assembled in a circular flexible freestanding film with a diameter of 8.4 cm and thickness of ~48 μm. The calcination of the zinc carbonate hydroxide nanobelts at 300 °C under normal atmospheric condition results in the formation of ZnO nanowires. The zinc carbonate hydroxide nanobelts and resultant ZnO nanowires are characterized by XRD, SEM, TEM, TG-DSC, PL, and impedance measurement. The characterization results indicate that the ZnO nanowires exhibit unique nanostructure characterized by long chains of closely attached ZnO nanocrystals with ZnO/ZnO nanocrystal junctions. The unique ZnO nanowire-based UV photodetector exhibit much higher photoresponse currents (at the milliampere level) and on/off current ratio (~1000) than ZnO nanocrystal-based UV photodetector. Under the UV irradiance of 120 mW cm(-2) and low applied voltage of 0.5 V, the peak photoresponse current and on/off current ratio of the ZnO nanowire photodetector are 56 and 36 times higher than those of the ZnO nanocrystal UV photodetector, respectively. The reason for the superior photodetection performance of the ZnO nanowires over the ZnO nanocrystals is discussed.