Preparation And Performances Of Aligned Semieonductor Nanowire Arrays

ZnO and TiO2are excellent optoelectronic semieonductor nanomaterials.and they have similar energy band structure and band gap degree. Vertically aligned ZnO and TiO2nanowire arrays on substrate with more excellent performance, are widely used in nano-electronic devices such as solar cells,light-emitting diodes, sensors, UV detectors, and so forth. In addition, combined the properties of photo-sensitive, gas-sensitive of ZnO and TiO2semiconductor, conducting polymer PANI and the P-N junction characteristics,they can also produce a variety of optoelectronic devices, so can further improve the performance of ZnO and TiO2semiconductor nanomaterials and widen their application field. In order to provide a solid materials foundation for the devices, highly ordered and uniform distribution of ZnO and TiO2nanowire arrays were synthesized by electrochemical deposition method and hydrothermal, respectively. The main contents and results are as follows:(1) Highly ordered ZnO nanowire arrays were synthesized on transparent conductive fluorine-doped tin oxide (FTO) substrates by electrochemical deposition method with controlling the electrodeposition parameters. During the optimization of experimental parameters, there were ZnO nanosheets, ZnO nanowire in the interspace of nanosheets on FTO substrates, it showed that different experimental conditions impacted on the morphology. So the formation mechanism of the ZnO nanowires was discussed in detail.The structure and mophology of ZnO nanowire arrays were analyzed by scanning electron microseope(SEM), X-ray diffraction(XRD) and photoluminescence spectra(PL).The results revealed that the prepared ZnO nanowire arrays with good crystal quality and optical-electrical properties.(2) Vertically aligned TiO2nanowire arrays were synthesized directly on transparent conductive fluorine-doped tin oxide (FTO) substrates by hydrothermal method with tetrabutyl titanate, deionized water and hydrochloric acid because the lattice mismatch of FTO conductive glass conductive layer and the TiO2is only2%. Highly ordered TiO2nanowire arrays were prepared on the FTO substrate by Optimizing of experimental parameters. The structure and mophology of TiO2nanowire arrays have been analyzed by scanning electron microseope(SEM),X-ray diffraction(XRD), selected-area electron diffraction(SEAD) and Transmission electron microscopy(TEM).The results of XRD and SEAD showed that the TiO2nanowire arrays prepared on FTO were rutile. From high magnification SEM, TEM and XRD can be seen, each TiO2nanowire was gathered together with dozens of4-7nm small nanowires which have good crystal structure. In the TiO2nanowires diameter direction, adjacent spacing of the crystal plane is approximately0.325nm, corresponding to the (110) crystal plane of rutile TiO2crystals, which indicates that the nanowires have a [001] oriented growth.(3) Acid-doped p-type conductive polymer PANI nanowires were synthesized by the solution method and characterized by SEM and EDS. The sandwich nanodevices FTO-ZnO/PANI-FTO,FTO-TiO2/PANI-FTO and FTO-TiO2/PANI/TiO2-FTO were assembled with the P-N junction characteristics between ZnO, TiO2nanowire arrays and PANI nanowires film. The I-V characteristic curve of sandwich devices revealed that P-N junction have rectifier effect; the I-t characteristic curve of sandwiches devices showed the nanodevices have good photosensitivity and reversibility.