Growth and Characterization of ZnO nanowires for various Sensor Applications (original) (raw)
Related papers
Growth and characterization of ZnO nanowires for optical applications
Laser Physics, 2013
In the present work, cerium oxide CeO 2 nanoparticles were synthesized by the sol-gel method and used for the growth of ZnO nanorods. The synthesized nanoparticles were studied by x-ray diffraction (XRD) and Raman spectroscopic techniques. Furthermore, these nanoparticles were used as the seed layer for the growth of ZnO nanorods by following the hydrothermal growth method. The structural study of ZnO nanorods was carried out by means of field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and XRD techniques. This study demonstrated that the grown ZnO nanorods are well aligned, uniform, of good crystal quality and have diameters of less than 200 nm. Energy dispersive x-ray (EDX) analysis revealed that the ZnO nanorods are composed only of zinc, cerium as the seed atom, and oxygen atoms, with no other impurities in the grown nanorods. Moreover, a photoluminescence (PL) approach was applied for the optical characterization, and it was observed that the near-band-edge (NBE) emission was the same as that of the zinc acetate seed layer, however the green and orange/red emission peaks were slightly raised due to possibly higher levels of defects in the cerium oxide seeded ZnO nanorods. This study provides an alternative approach for the controlled synthesis of ZnO nanorods using cerium oxide nanoparticles as the seed nucleation layer, improving both the morphology of the nanorods and the performance of devices based upon them.
Synthesis and enhanced properties of Cerium doped ZnO nanorods
Ceramics International, 2014
Pure and 1 mol% Ce doped ZnO nanoparticles were synthesized by the wet chemical solution route. Ce doping shifted XRD peaks to a slightly higher angle. Transmission electron microscopy revealed the rod type morphology of both the nanoparticles with decrease in length and diameter of Ce doped ZnO in the range of 80-120 nm and 16-20 nm, respectively. A sharp lower cutoff at 190 nm and reduction in the bandgap from 3.22 eV to 3.08 eV were observed in UV-vis study. Ce 3 þ doping resulted in the broadening of the green emission photoluminescence band. An enhanced ionic behavior in doped ZnO resulted in a significant increase in dielectric constant (ε ¼ 368), piezoelectric coefficient (d 33 ¼30 pC/N) and ferroelectric properties (P r ¼40 μC/cm 2 ). Rectifying I-V characteristics were observed for both the nanoparticles.
Journal of Alloys and Compounds, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Effect of doping precursors on the optical properties of Ce-doped ZnO nanorods
Thin Solid Films, 2011
We have investigated the use of different cerium precursors for fabrication of Ce doped ZnO nanorods by electrodeposition. ZnO nanorods fabricated with different Ce precursors had similar morphology, but very different optical properties. The influence of annealing in oxygen at different temperatures on the optical properties of Ce doped ZnO nanorods was also studied. The as-grown samples exhibited very different ratios of ultraviolet to visible (defect) emission. The relative contributions of green and orange-red emissions in the emission spectra of annealed samples were also dependent on the precursor used, indicating that the types and concentrations of native defects were dependent on the precursor used. To explore the possibility of applications of these nanorods in ZnO-based devices, nanorods were also grown on p-GaN substrates. Two different Ce precursors in this case resulted in different current-voltage curves, as well as different electroluminescence and photoluminescence spectra of the devices. Obtained results are discussed.
Effect of Growth Time on the Characteristics of ZnO Nanorods
ZnO nanorods were successfully synthesized via two stages, that is deposition of ZnO seed layers on ITO substrate and growth of ZnO nanorods via solvothermal method. A characterization by using XRD was employed to investigate the structure and size of the crystals. SEM characterization was used to study the size and morphology of the particles. UV-Vis and FTIR characterizations were used to investigate the bandgap and functional group of the samples. The data analysis presented that the ZnO particles had a crystal structure of hexagonal with rod morphology. The diameter size of the ZnO nanorods growth on the substrate surface for the growth time of 4, 6, and 8 hours were respectively 138, 230, and 236 nm with the length of the rods of 570, 934, and 1280 nm, respectively. The bandgaps of the ZnO nanorods for growth times of 4, 6, and 8 hours were respectively 3.14, 3.12, and 3.05 eV, while the ZnO seed layers had 3.22 eV band gap. FTIR spectrum showed that the main peaks were 400-515, 870, and 1250 cm-1 showing the functional groups of ZnO and H-C-N.
Field emission studies on electrochemically synthesized ZnO nanowires
Ultramicroscopy, 2009
Nanocrystalline zinc oxide (ZnO) films were synthesized using cathodic reduction of Zn foil in aqueous electrolyte of different molar concentrations containing ZnCl 2 and H 2 O 2 , followed by annealing at 400 1C in air. An X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used for characterization. The XRD patterns exhibited a set of well-defined diffraction peaks corresponding to the wurtzite phase of ZnO. SEM and TEM images clearly revealed the formation of randomly oriented ZnO nanowires having lengths of several microns and diameters less than 100 nm. From the field emission studies, the threshold field values, required to draw emission current density of 1mA/cm2werefoundtobe1.44,1.36and1.5V/mmfornanowiressynthesizedusing0.002,0.004and0.016Melectrolyteconcentrations,respectively.AllFolwer−Nordheim(F−N)plotsshowednon−linearbehaviorindicatingsemiconductingnatureoftheemitters.TheZnOnanowiresexhibitedgoodemissioncurrentstabilityatthepre−setvalueof1 mA/cm 2 were found to be 1.44, 1.36 and 1.5 V/mm for nanowires synthesized using 0.002, 0.004 and 0.016 M electrolyte concentrations, respectively. All Folwer-Nordheim (F-N) plots showed non-linear behavior indicating semiconducting nature of the emitters. The ZnO nanowires exhibited good emission current stability at the pre-set value of 1mA/cm2werefoundtobe1.44,1.36and1.5V/mmfornanowiressynthesizedusing0.002,0.004and0.016Melectrolyteconcentrations,respectively.AllFolwer−Nordheim(F−N)plotsshowednon−linearbehaviorindicatingsemiconductingnatureoftheemitters.TheZnOnanowiresexhibitedgoodemissioncurrentstabilityatthepre−setvalueof10 mA over a duration of 6 h. The simplicity of the synthesis route coupled with the promising emission properties made the electrochemically synthesized ZnO nanowires a suitable candidate for high-current density applications.
Synthesis and Characterization of Zinc Oxide (ZnO) Nanowire
Journal of Nanomedicine & Nanotechnology, 2015
Nanowires are structures that have a lateral size constraint to tens of nanometers or less and an unconstrained longitudinal size. The syntheses and characterization of ZnO nanowire with hexagonal structure was successfully achieved using chemical bath deposition technique. The nanowires obtained were further characterized by scan electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and spectrophotometer. The SEM micrographs revealed the morphology of ZnO nanowires with diameter 170.3 nm and 481 nm. This revealed that the pH 8.1 of the bath solution and the optimized value form ZnO nanowires with hexagonal shape at top surface. The XRD pattern of the samples revealed ZnO nanowire have hexagonal crystallite structure. Where upon the crystallite size supported increased annealing temperature (0.536 nm, 0.541 nm and 0.557 nm at 100°C, 150°C and 200°C respectively). The EDX analysis revealed the elemental compositions of samples and confirmed the presence of Zn and O2. The results of the optical analysis showed that ZnO nanowire have high absorbance in the ultraviolet and infrared regions with high transmittance in the visible region. The absorbance of the nanowire increases with increasing annealing temperature. Its high absorbance in the ultraviolet region suggest it applicability as solar harvester for trapping solar energy, used for photovoltaic panel with capacity to converting sunlight radiation directly to electricity for commercial or industrial purposes.
A Comparison of ZnO Nanowires and Nanorods Grown Using MOCVD and Hydrothermal Processes
Journal of Electronic Materials, 2013
A comparison of ZnO nanowires (NWs) and nanorods (NRs) grown using metalorganic chemical vapor deposition (MOCVD) and hydrothermal synthesis, respectively, on p-Si (100), GaN/sapphire, and SiO 2 substrates is reported. Scanning electron microscopy (SEM) images reveal that ZnO NWs grown using MOCVD had diameters varying from 20 nm to 150 nm and approximate lengths ranging from 0.7 lm to 2 lm. The NWs exhibited clean termination/tips in the absence of any secondary nucleation. The NRs grown using the hydrothermal method had diameters varying between 200 nm and 350 nm with approximate lengths between 0.7 lm and 1 lm. However, the NRs grown on p-Si overlapped with each other and showed secondary nucleation. x-Ray diffraction (XRD) of (0002)-oriented ZnO NWs grown on GaN using MOCVD demonstrated a full-width at half-maximum (FWHM) of 0.0498 (h) compared with 0.052 (h) for ZnO NRs grown on similar substrates using hydrothermal synthesis, showing better crystal quality. Similar crystal quality was observed for NWs grown on p-Si and SiO 2 substrates. Photoluminescence (PL) of the NWs grown on p-Si and SiO 2 showed a single absorption peak attributed to exciton-exciton recombination. ZnO NWs grown on GaN/sapphire had defects associated with oxygen interstitials and oxygen vacancies.