The Fabrication And Characterization Of ZnO Nanowires UV Photodetectors

The synthesis and applications of ZnO nanomaterials is a highly desired objective in nanotechnology. ZnO material has a wide and direct band gap (Eg=3.37eV), high exciton binding energy (60meV) and stable physical and chemical properties. Based on unique nanomaterials properties and the advantage of ZnO material, ZnO nanowires have been promising application potential in optoelectronics. To avoid the short circuit, the vertical ZnO nanodevices have to fill the insulating material between the nanowires generally. Howerve the photoresponse theory of ZnO Nano-UV detectors is related to surface states of the ZnO nanowires. To the structure of ZnO nanowires UV detectors, the plane structure is better than the vertical structure. The reason was that the planar devices can take full advantage of the large surface-to-volume ratios of ZnO nanowires. Therefore, combines the laboratory conditions, the main work of this dissertation are to fabricate and the properties of plane ZnO nanowires UV detector:1. By controlling the growth steps, the ZnO nanowires could grow horizontally on the side surface of the ZnO interdigital electrode by the hydrothermal method. The horizontal ZnO nanowires could connect with each other between the interelectrodes to make the electrons passing through the different electrodes. The ZnO nanowires UV detector showed a narrow ultraviolet photoresponse with the response peak at 379 nm.2. ZnO nanowires could be order arrayed between the interdigital electrodes by using dielectrophoresis method. First, we design and grow long ZnO nanowires of 10μm by twice hydrothermal method. Then, the ZnO nanowire UV detector with plane structure was fabricated under the high frequency electric field. This nanowire UV detector had a high responsivity up to 40 A/W. It was observed by time-resolved analysis that the rise and decay state of the optical response were all existence of surface states and deep level defects relaxation related to two processes analyzed by time-resolved.3. ZnO nanowires were modified by silver nanoparticles. The intensity of photoluminescence was decreased with the increasing of the Ag ion concentration. The responsivity of Ag modified ZnO nanowires detector was 77 times larger than the as-grown ZnO nanowires device.4. The annealing treatment was significantly improved the recovery time of ZnO nanowires UV detector. The results of the photoluminescence indicated that this improvement was relevant with the change of ZnO nanowires surface states.