Peculiarity of seed-layer synthesis and morphometric characteristics of ZnO nanorods (original) (raw)
Related papers
2017
ZnO nanorods were prepared by a hybrid deposition technique. ZnO seed layers were deposited onto glass substrates by sol-gel spin coating technique. ZnO nanorods were synthesized onto seed layers by chemical bath deposition method in very short time like 30 minutes. Effects of seed layer and the thickness of the seed layer on the crystalline structure and morphology of the ZnO nanorods were investigated using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). It was established that ZnO nanorod does not form without seed layer. It was found that ZnO nanorods synthesized onto seed layer have a perfect crystalline wurzite structure with a preferentially orientation of (002). The intensity of (002) peak strongly increased as the thickness of seed layer increased. It was determined that the majority of synthesized ZnO nanorods on the seed layers are vertical. An increase was observed in the density and the length of the vertically synthesized ZnO nanorods by increasing the thickness of seed layer. The increased thickness of seed layers led to improve the crystalline quality and morphological properties of ZnO nanorods.
Selective growth of ZnO nanorods by patterning of sol-gel-derived thin film
Journal of Electroceramics, 2006
An effective method of fabricating micro and sub micro patterned zinc oxide nanorods without a transient metal catalytic assistants via hydrothermal synthesis using micro molding technique was presented. Micro molding of sol-gelderived precursor layer was clearly accomplised by conformal contact of elastomeric molds with various kinds of patterns. The selective growth of the nanorods over a large area of the pre-patterned seed layer was observed with a pattern feasibility of 250 nm. The orientation of the nanorods was normal to the seed layer while characteristic sizes of the rod didn't show any dependence on the diameter of the seed particles. Presented synthetic process can provide simpler way of fabricating an array of semiconductor one-dimensional nanostructures.
Highly Textured Seed Layers for the Growth of Vertically Oriented ZnO Nanorods
Crystals, 2019
One dimensional ZnO nanostructures prepared by favorable and simple solution growth methods are at the forefront of this research. Vertically oriented ZnO nanorods with uniform physical properties require high-quality seed layers with a narrow size distribution of the crystallites, strong c-axis orientation, and low surface roughness and porosity. It has been shown that high quality seed layers can be prepared by the sol–gel process. The sol–gel process involves three essential steps: preparation of the sol, its deposition by dip coating, and thermal treatment comprising preheating and annealing. We put emphasis on the investigation of the heat treatment on the properties of the seed layers and on the vertical alignment of the nanorods. It was demonstrated that for the vertical alignment of the nanorods, the preheating step is crucial and that the temperatures reported in the literature have been too low. With higher preheating temperatures, conditions for the vertical alignment of ...
International Journal of Electrochemical Science
Highly ordered and uniform vertical ZnO nanorod arrays were synthesized by a facile and lowtemperature sol-gel method using two different seed layers [i.e., Mg-doped ZnO (MZO) and Al,Mgdoped ZnO (AMZO)] and deposited by spin coating technique. Field-emission scanning electron microscopy images confirmed that vertical, denser, and orderly ZnO nanorods are grown on AMZO seed layer compared with that synthesized on MZO seed. UV-visible spectra indicated that Al and Mg additives could significantly enhance the optical transparency and induce a blueshift in optical band gap of ZnO films. The electrical property shows that ZnO nanorods grown on AMZO seed have lower resistivity of 2.30 Ω cm than that on MZO seed (7.67 Ω cm). The electrical conductivity of ZnO films grown on co-doped seed layer could be tailor and this might be effectively inducing the geometric growth of ZnO films by sol-gel.
Growth of ZnO nanorod arrays by one-step sol–gel process
Journal of Sol-Gel Science and Technology, 2016
ZnO nanorods are usually formed by two-step method. In the first step, a seed layer is coated on substrate and then the second treatment by hydrothermal method is employed for formation of nanorods. Here, we report that ZnO nanorods can be directly coated on glass substrates by sol-gel dip coating technique without the second treatment. The effect of coating layers on morphological, structural, electrical, and optical properties was studied. According to the cross-sectional SEM images of the produced ZnO nanorods, a seed layer was spontaneously observed. The diameter of the ZnO nanorods was varied between 200 nm and 1 lm with coating thickness. The effect of the zinc nitrate tetrahydrate and zinc chloride precursors on the preparation of the ZnO nanorods was also investigated. And, it was found that the zinc chloride precursor exhibited formation of nanorods on the glass substrates. According to the Hall effect measurements, the ZnO nanorods exhibited mobility as high as 95 cm 2 (Vs)-1. The X-ray diffraction and electrical studies indicated that highly pure crystalline ZnO nanorods could be obtained by the one-step solution method.
Seed layer morphology influencing on ZnO nanorod growth by hydrothermal synthesis
Transactions of the Materials Research Society of Japan, 2018
The structure of seed layers has been considered as a significant factor to dictate the subsequent growth of ZnO nanorods. We carefully studied seed layer structures such as crystallinity, surface crystal orientations, and grain sizes to investigate their effect on ZnO nanorod growth during hydrothermal synthesis. The structure of seed layers was changed by controlling their thickness and further annealing treatments at 200-1000 °C. Among several parameters of seed layer structure, the grain size and the surface crystal orientation were found to make a noticeable change in the morphology of ZnO nanorods. Thick ZnO nanorods were produced on large grains while densely aligned products were observed on the seed layer surface with c-axis orientation. In addition, at the early stage of synthesis, we observed ZnO nanorods with a diameter much smaller comparing to the size of grains consisting of poly-and single crystal. This explains that the nucleation of ZnO crystals start on c-axis oriented domains, and they grow in a length favorably and in diameter gradually, resulting in the formation of ZnO nanorods with the integration of tightly aligned products.
Crystal growth of nanostructured zinc oxide nanorods from the seed layer
Materials Science Poland, 2018
One-dimensional (1D) zinc oxide (ZnO) nanostructures (nanorods) were synthesized on a glass slide and fluorine-doped tin oxide (SnO 2 /F or FTO) coated glass (FTO/glass) by a wet chemical method. The structural, morphological and optical analyses of the as-deposited ZnO nanostructures were performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and UV-Vis spectroscopy, respectively. The XRD results showed that the nanostructures as-deposited on the glass and the FTO/glass substrates were of ZnO wurtzite crystal structure, and the crystallite sizes estimated from the (0 0 2) planes were 60.832 nm and 64.876 nm, respectively. The SEM images showed the growth of densely oriented ZnO nanorods with a hexagonal-faceted morphology. The UV-Vis absorption spectrum revealed high absorbance properties in the ultraviolet range and low absorbance properties in the visible range. The optical energy band gap of the ZnO nanostructure was estimated to be 3.87 eV by the absorption spectrum fitting (ASF) method.
Advanced Materials Research, 2013
ZnO nanorods were successfully grown on Au coated Si substrate and Si bare substrate. The growth was using sol-gel immersion method at different deposition time which is 2, 4, 6, 8, 10 and 12 hours. In the presence of Au, growth rate of nanorods is much faster as it performs as a catalyst by decreasing the growth time of ZnO nanorods to half compared to growth on Si substrate without Au coated. Using Scanning Electron Microscope (SEM), changes in growth of nanorods at different deposition time was captured and the structural properties are discussed.
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.
Malaysian Journal of Fundamental and Applied Sciences
In this work, zinc oxide (ZnO) nanorods structure in the form of thin film have been grown on soda-lime glass (SLG) substrate incorporating two simple steps. Firstly, ZnO seed layer was pre-deposited onto the SLG substrate by the thermal evaporation method. During this process, the oxidation temperatures were varied in the range of 450 oC to 650 oC annealed for 3 hours. Then, the nanorods structure were grown on the surface of the seed layer by sol-gel immersion method with the use of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and hexamethylenetetramine (HMT) in deionized (DI) water. The optical, structural and morphological properties at different oxidation temperatures were studied using UV-Vis-NIR spectroscopy, X-ray diffraction (XRD) and Field-enhanced Scanning Electron Microscopy (FeSEM). The surface morphology results revealed the formation of hexagonal shaped ZnO on top of the seed layer as a result of heterogeneous nucleation. X-ray diffraction results show that the c-axis ori...