Investigating The Annealing Effect on The Conventional Growth of ZnO Nanorod Through Electrical Characterization (original) (raw)
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Characterisation of ZnO nanorod arrays grown by a low temperature hydrothermal method
Philosophical Magazine, 2012
In this paper, growth steps of well defined ZnO nanorod arrays deposited on seeded substrates were investigated. To obtain ZnO seed layer on glass substrates, a successive ionic layer adsorption and reaction (SILAR) method was used and then ZnO nanorods were grown on seed layer using a chemical bath deposition (CBD) method. The effects of seed layer and deposition time on morphology, crystallographic structure (e.g. grain size, microstrain and dislocation density) and electrical characteristics of ZnO nanorods were studied. From the SEM micrographs, it could be seen that the ZnO nanorods densely covered the substrate and were nearly perpendicular to the substrate surface. The XRD patterns showed that the ZnO nanorod arrays had a hexagonal wurtzite structure with a preferred orientation along the (002) plane. An increase in deposition time resulted in an increase in the intensity of the preferred orientation and grain size, but a decrease in microstrain and dislocation density. Electrical activation energies of the structures were calculated as 0.15-0.85 eV from current-temperature characteristics. It was concluded that the morphologies of the structures obtained in this study via a simple and fast solution method can provide high surface areas which are important in areadependent applications, such as solar cells, hydrogen conversion devices, sensors, etc.
Some Distinct Attributes of ZnO Nanorods Arrays: Effects of Varying Hydrothermal Growth Time
Materials
This study investigates the growth time effect on the structural, morphological, optical, and photoelectrochemical characteristics of highly oriented ZnO nanorod arrays (ZNRAs). The nanorod arrays were grown on ITO substrates using the unified sol-gel spin coating and hydrothermal techniques. ZnO nanoparticles (ZNPs) were synthesized using the sol-gel spin coating method. In contrast, the hydrothermal method was used to grow the ZnO nanorods. The hydrothermal growth time investigated was between 4 and 12 h. The synthesized ZNRAs were used as the photoanode electrodes to investigate their photoelectrochemical (PEC) electrode potency. The as-prepared ZNRAs were characterized using various analytical tools to determine their structures, morphologies, optical, and photoelectrochemical traits. EDX spectra showed the presence of uncontaminated ZnO chemical composition, and FTIR spectra displayed the various functional groups in the samples. A rod-shaped ZnO nanocrystallite with mean lengt...
Growth of ZnO nanorods on different substrates using hydrothermal method
Malaysian Journal of Fundamental and Applied Sciences, 2020
Zinc oxide (ZnO) nanorods have been grown on different substrates, i.e. gold film-coated BK-7 glass (Au-film/BK7), microscope glass slide (MGS), silicon oxide film-coated silicon (SiO2-film/Si), to investigate the effects of different substrates on its material properties. The growth process was started by dipping substrates in zinc acetate solution to fabricate a seed layer, followed by growing the ZnO nanorods in zinc nitrate tetrahydrate solution based on hydrothermal method at 95 °C for 6 hour. In this process, seed layer and ZnO nanorods were annealed at 350 °C for 2 hours. The characterization results using X-ray diffraction and field effect scanning electron microscope showed that ZnO nanorods were successfully grown homogenously and mostly in vertical direction with hexagonal wurtzite structure. The diameter size of ZnO nanorods was significantly influenced by the type of material substrate. ZnO nanorods on Au-film/BK-7 glass have the smallest diameter size of (239±51) nm, w...
Properties of ZnO nanorods grown by hydrothermal synthesis on conductive layers
Crystal Research and Technology, 2014
Zinc oxide nanorods (ZnO NRs) were grown in water solution on different conductive substrates. In particular, several metal layers, such as Cu, Ni, Pt, Ag, Au, deposited on silicon substrates, and F-doped SnO 2 (FTO) coated-glass wafers were investigated as bottom electrodes and their influence on the properties of the synthesized ZnO nanorods were studied. The samples were characterized by scanning electron microscopy, X-ray diffraction, atomic force microscopy, current -voltage (I -V) and photoluminescence measurements. We obtained vertically aligned ZnO nanorod arrays on all the considered substrates, proving how ease and reproducible is the hydrothermal growth of ZnO nanorods on different conductive layers. We here show how the morphology and the optical and electrical features of the array depend on the conductive material deposited as bottom layer.
PLoS ONE, 2012
In this study, zinc oxide (ZnO) nanorod arrays were synthesized using a simple hydrothermal reaction on ZnO seeds/nsilicon substrate. Several parameters were studied, including the heat-treatment temperature to produce ZnO seeds, zinc nitrate concentration, pH of hydrothermal reaction solution, and hydrothermal reaction time. The optimum heat-treatment temperature to produce uniform nanosized ZnO seeds was 400uC. The nanorod dimensions depended on the hydrothermal reaction parameters. The optimum hydrothermal reaction parameters to produce blunt tip-like nanorods (770 nm long and 80 nm in top diameter) were 0.1 M zinc nitrate, pH 7, and 4 h of growth duration. Phase analysis studies showed that all ZnO nanorods exhibited a strong (002) peak. Thus, the ZnO nanorods grew in a c-axis preferred orientation. A strong ultraviolet (UV) emission peak was observed for ZnO nanorods grown under optimized parameters with a low, deep-level emission peak, which indicated high optical property and crystallinity of the nanorods. The produced ZnO nanorods were also tested for their UV-sensing properties. All samples responded to UV light but with different sensing characteristics. Such different responses could be attributed to the high surface-to-volume ratio of the nanorods that correlated with the final ZnO nanorods morphology formed at different synthesis parameters. The sample grown using optimum synthesis parameters showed the highest responsivity of 0.024 A/W for UV light at 375 nm under a 3 V bias.
Journal of Nanomaterials, 2011
We investigated the influence of the pH value, precursor concentration (C), growth time and temperature on the morphology of zinc oxide (ZnO) nanostructures. The pH of the starting solution was varied from 1.8 to 12.5. It was found that the final pH reaches an inherent value of 6.6 independently of the initial pH solution. Various ZnO structures of nanotetrapod-like, flower-like, and urchin-like morphology were obtained at alkaline pH (8 to 12.5) whereas for pH solution lower than 8 rod-like nanostructures occurred. Moreover, we observed the erosion of the nanorods for a pH value less than 4.6. By changing the concentrations the density and size were also varied. On going from a high (C>400 mM) to lower (C<25 mM)C, the resulted ZnO nanostructures change from a film to nanorods (NRs) and finally nanowires (NWs). It was also found that the length and diameter of ZnO NRs follow a linear relation with time up to 10 hours, above which no further increase was observed. Finally the e...
Comparison between ZnO nanorods grown via hydrothermal and electrochemical deposition techniques for transducer fabrication, 2020
This paper presents the comparison between ZnO nanorod arrays grown using hydrothermal and electrochemical deposition techniques on a seedless ITO glass substrate. For electrochemical deposition, a two-electrode setup was used during the growth of the 1D ZnO nanorods in a zinc nitrate hexahydrate electrolyte. While an equimolar of zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) dissolved in water was used for the hydrothermal technique. The study showed that the concentration of Zinc nitrate hexahydrate, temperature, and voltage had a huge effect on the growth rate and diameter of the nanorods. A high density of hexagonal ZnO nanorods were successfully grown along the c-axis over the entire seedless-ITO coated substrates in less than 1 hour using the electrochemical deposition technique. While the ZnO nanorods grown using the aqueous solution technique showed poor growth, crystallization and took at least 24 hours for growth time. Then the ZnO nanorods were studied and characterised using atomic force microscopy (AFM), scanning electron microscopy and X-ray diffraction (XRD). In this paper, the ZnO nanorods are used to manufacture a piezoelectric nanogenerator. Electrochemical deposition is by far the simplest growth technique to use, as it requires the lowest temperature and atmospheric pressure. Moreover, it is highly cost-effective and scalable than any other methods. Zinc oxide nanorods grown using the electrochemical deposition technique were observed to show better crystallization and piezoelectric properties than those grown via the aqueous solution technique. ZnO nanorods nanoscale devices hold a promising future for their application in photocatalysis, solar cells, optical and biosensing devices.
Morphological, structural, and electrical characterization of sol-gel-synthesized ZnO nanorods
Journal of Nanomaterials, 2013
ZnO nanorods were grown on thermally oxidized p-type silicon substrate using sol-gel method. The SEM image revealed highdensity, well-aligned, and perpendicular ZnO nanorods on the oxidized silicon substrate. The XRD profile confirmed the c-axis orientation of the nanorods. PL measurements showed the synthesized ZnO nanorods have strong ultraviolet (UV) emission. The electrical characterization was performed using interdigitated silver electrodes to investigate the stability in the current flow of the fabricated device under different ultraviolet (UV) exposure times. It was notified that a stable current flow was observed after 60 min of UV exposure. The determination of stable current flow after UV exposure is necessary for UV-based gas sensing and optoelectronic devices.
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.
Effect of heat and time-period on the growth of ZnO nanorods by sol–gel technique
Optik - International Journal for Light and Electron Optics, 2012
Sol-gel routes to metal oxide nanoparticles in organic solvents under exclusion of water have become a versatile alternative to aqueous methods. We focus on the preparation of well-aligned ZnO nanorod arrays using non-aqueous sol-gel synthesis route, where ZnO nanorods arrays have been grown on glass substrates. This work provides a systematic study of controlled morphology and crystallinity of ZnO nanorod arrays. The investigation demonstrates that the synthesis process conditions of ZnO thin film have strong influences on the morphology and crystallinity of the ZnO nanorod arrays grown thereon, where non-aqueous process offers the possibility of better understanding and controlling the reaction pathways on the molecular level, enabling the synthesis of nanomaterials with high crystallinity and well-defined, uniform particle morphologies. Here the annealing temperature plays an important role on the growth of nanostructures of the ZnO grains and nanorod arrays. The scanning electron microscopy (SEM) image shows that the growth of ZnO nanorod arrays are high-quality single crystals growing along the c-axis perpendicular to the substrates. A detailed analysis of the growth characteristics of ZnO nanostructures as functions of growth time is also reported.