Properties Of ZnO Nanorods Research Articles

Effects of Ga Doping on Structural and Optical Properties of ZnO Nanorods

Effects of Ga Doping on Structural and Optical Properties of ZnO Nanorods

The improved piezoelectric properties of ZnO nanorods with oxygen plasma treatment on the single layer graphene coated polymer substrate (Phys. Status Solidi A 2∕2014)

The improved piezoelectric properties of ZnO nanorods with oxygen plasma treatment on the single layer graphene coated polymer substrate (Phys. Status Solidi A 2∕2014)

Study the effect of functional molecule types on the surface properties of ZnO nanorods

To better understand the effect of functional molecule types to the surface properties of ZnO nanorods, three organic molecules – ethylenediamine, sodium citrate and butanethiol were used for the surface modification of ZnO nanorods.

Synthesis of ZnO nanorods on ZnO/ITO seed layer by electrochemical method and its application in solar cell device

In this paper, we study on the effects of ZnO nanorods /seed ZnO on properties of hybrid solar cells. ZnO nanorods fabricated by electrochemical method of two-step stable flow of liquid Zn(NO3)2. 6H2O (0.005 M) and C6H12N4 (0.005 M). Morphology and optoelectronic properties of ZnO nanorods were studied by SEM images, UV-VIS transmission spectra, X-ray diffraction and photoluminescence spectrum. Elaboration of hybrid solar cells by inserting ZnO nanorods on organic photoactive layer of P3HT:PCBM and ITO, as result the solar cell conductivity performance is significantly improved. Experimental results show that ~ 1,392 mA/cm2 Jsc, Voc ~ 0.49 V, FF = 0.32, and PCE = 0.23%.

Effect of Temperature on Structural and Optical Properties of ZnO Nanorods by Hydrothermal Method

The ZnO nanorods were prepared at 130 °C, 160 °C and 190 °C for 6 h by hydrothermal method. The structural and optical properties of ZnO nanorods were invesitigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). XRD pattern analysis showed that the ZnO nanorods are the hexagonal structure (space group P63 mc). No other crystal phases, such as Zn and Zn (OH)2 were detected. FT-IR study identified the sharp peak that appeared at 573 cm-1 is related with the ZnO stretching mode. Also, SEM images revealed that the diameter of a single ZnO crystal ranges from 100 to 300 nm and the length ranges from 1 to 3 μm.

Structural and photoluminescence studies of highly crystalline un-annealed ZnO nanorods arrays synthesized by hydrothermal technique

To investigate the effect of a seed layer on the growth and properties of ZnO nanorods using hydrothermal technique, various thickness of sputter deposited ZnO thin films were used. The changes in crystallinity, orientation, and optical properties of the nanorods synthesized on these ZnO thin films were examined. These properties were studied simultaneously in two series of samples, wherein in one series the nanorods were unannealed while in the other series they were annealed. Structural characterization revealed that both categories of nanorods were highly crystalline, with a hexagonal phase, and grew along the [0001] direction. The density of the nanorods per unit area increased as the thickness of the seed layer decreased. We also found that the defect related emission in photoluminescence spectra was quite low in both the annealed and non-annealed samples series. Typically, the decay curves obtained from these ZnO nanorods show a combination of two exponential decays. The nonradiative fast decay component was affected by the thickness of the seed layer and its values were higher than those of previously reported ZnO nanostructures grown by the hydrothermal technique. This comprehensive study shows that as grown nanorods lead directly to a high crystalline quality.

Study of frequency dependent electrical properties of ZnO nanorods

Purpose – The purpose of the current research is to use impedance spectroscopy to study the AC parameters that varied with frequency such as impedance, dielectric constant and conductivity of ZnO nanorods MSM structure in the range of 1 Hz to 10 MHz under atmospheric conditions.Design/methodology/approach – ZnO nanorods were grown on glass substrate using low cost sol‐gel method. 0.35 M seed solution was prepared by dissolving zinc acetate dihydrate in 2‐methoxyethanol and monoethanolamine which acts as a stabilizer was added drop‐wise. Prior to the deposition, glass slide was cut into pieces of 1.5 cm×2 cm. Ultra‐sonication process is used to clean the glass substrate using acetone, ethanol, and de‐ionized (DI) water for 5 min. The prepared seed solution was coated on glass substrate using spin coater at spinning speed of 3000 rpm for 30 s and then dried at 250°C for 10 min followed by annealing at 550°C for 2 h. The hydrothermal growth was carried out in aqueous solution of zinc nitrate hexahydrate (25 ...

Impact of first-step potential and time on the vertical growth of ZnO nanorods on ITO substrate by two-step electrochemical deposition

Abstract In this study, we analyzed the growth of ZnO nanorods on an ITO (indium doped tin oxide) substrate by electrochemical deposition using a two-step, continuous potential process. We examined the effect of changing the first-step potential as well as the first-step duration on the morphological, structural and optical properties of ZnO nanorods, measured via using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. As a result, vertical ZnO nanorods were grown on ITO substrate without the need for a template when the first-step potential was set to −1.2 V for a duration of 10 s, and the second-step potential was set to −0.7 V for a duration of 1190 s. The ZnO nanorods on this sample showed the highest XRD (0 0 2)/(1 0 0) peak intensity ratio and the highest PL near band edge emission to deep level emission peak intensity ratio (NBE/DLE). In this study, the nucleation for vertical ZnO nanorod growth on an ITO substrate was found to be affected by changes in the first-step potential and first-step duration.

Vertical growth of ZnO nanorods on ITO substrate by using a two-step-potential electrochemical deposition method

In this study, we grew vertical ZnO nanorods on indium-doped tin-oxide (ITO) substrate by using an electrochemical deposition. For the growth, we used a two-step, continuous potential process without a template, additives, catalysts or a seed buffer layer. The morphological, structural and optical properties of ZnO were investigated using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. The best test conditions resulted in the growth of vertical ZnO nanorods with a height of 550 nm and occurred when a first-step potential of −1.2 V was applied for 10 s, and a second-step potential of −0.7 V was applied for 1190 s. ZnO nanorods grown at the optimized growth condition show the strongest (002) peak intensity in the XRD spectrum and the highest near band edge emission over deep level edge emission (NBE/DLE) peak ratio of 76.26 and the lowest full width at half maximum (FWHM) of 144 meV in the photoluminescence spectrum. In our study, the structural and the optical properties of ZnO nanorods were highly improved, as compared with a constant single potential for 1200 s, when a first-step potential of −1.2 V was applied for 10 s and was followed by a second-step potential of −0.7 V which was applied for 1190 s.

Effects of annealing temperature on optical properties of ZnO nanorods with Mg0.2Zn0.8O capping layers

ZnO nanorods were grown on spin-coated ZnO seed layers by the hydrothermal method. The Mg0.2Zn0.8O capping layers were deposited on ZnO nanorods by the sol-gel method. The ZnO nanorods with Mg0.2Zn0.8O capping layers were annealed at 600°C. Temperature-dependent photoluminescence (PL) spectroscopy was carried out to investigate the mechanism governing the quenching behavior of the PL spectra. For the 12 K PL spectra, the peaks of the Mg0.2Zn0.8O capping layers, excitons bound to neutral donors (D0X), two-electron satellite transitions, donor-acceptor pairs, and free-to-neutral-acceptors and their longitudinal optical (LO) phonon replicas were observed at annealing temperatures from 600°C. At 12 K, the peak of the Mg0.2Zn0.8O capping layers was blue-shifted as the annealing temperature increased. The peaks of the D0X, free excitons and Mg0.2Zn0.8O capping layers merged and the PL intensity of the peaks decreased while the temperature increased from 12 to 300 K.

Physical and chemical contributions of a plasma treatment in the growth of ZnO nanorods

Abstract We analyzed the enhancement of optical and structural properties of ZnO nanorods by using a plasma treatment. In this study, seed ZnO nanorods were grown by hydrothermal synthesis for 1 h on a ZnO buffered Si substrate. The seed ZnO nanorods were then treated with an oxygen plasma. Next, ZnO was grown for an additional 4 h by hydrothermal synthesis. The resultant ZnO nanorods were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD) and photoluminescence (PL). The measurements showed that the plasma treatment of the seed ZnO nanorods increased the roughness of the buffer layer and the concentration of oxygen ions on the surfaces of the seed ZnO nanorods and the buffer layer, leading to improved optical and structural properties. In this study, we found that the plasma treatment on the seed ZnO nanorods enhanced the optical and structural properties of the ZnO nanorods.

Electro-optical and Structural Properties of Al-doped ZnO Nanorod Arrays Prepared by Hydrothermal Process

The undoped and Al-doped ZnO nanostructures were grown on ZnO/glass substrates using a low temperature hydrothermal process. The RF-sputtering method was utilized to prepare ZnO film on the glass substrates as a seed layer for subsequently hydrothermal growth of ZnO nanostructures. The properties of ZnO nanorods were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and room- temperature photoluminescent spectrometer (PL).The X-ray diffraction patterns show that both undoped and Al-doped ZnO nanorod arrays are grown with (002) preferred orientation. Undoped quasi-aligned ZnO nanorods were successful synthesized by this method. The current-voltage curves of Al-doped ZnO nanorod arrays exhibited a slightly higher current response than the as-grown ones. This result confirms that N-type doping of aluminum can be accomplished effectively by this method.

Effect of solution concentration on the functional properties of ZnO nanostructures: Role of Hexamethylenetetramine

In this research, ZnO nanorods have been successfully synthesized via wet chemical method. XRD results revealed the single phase nature with the wurtzite structure of the as prepared ZnO nanorods. By only varying the concentration of Hexamethylenetetramine (HMT) in the solution, morphology of ZnO changed from hexagonal facet nanorods to pencil like nanorods and size of nanorods also changed. The band gap of as-synthesized ZnO nanorods was found to increase with increasing the concentration of HMT in the solution. The narrow full-width at half-maximum (FWHM) of the UV emission of PL spectra indicated that the grown ZnO nanorods have high crystal quality and is well matched with the obtained XRD results. These results revealed that the concentration of Hexamethylenetetramine plays a vital role to control the properties of ZnO nanorods.

Influence of Growth and Annealing Temperatures on the Properties of ZnO Nanorods Synthesized by Dip Coating Method

A novel and simple approach is reported to fabricate ZnO nanorods. Zinc acetate dihydrate, ethanol and de-ionized water were used to prepare seed layer. Zinc nitrate and hexamethylenetetramine solution were used for growth of ZnO nanorods. The ZnO nanorods were grown at two different temperatures of 90°C and 120°C and annealed at three different temperatures of 300°C, 400°C and 500°C in air atmosphere. Nanorod growth temperature and annealing temperature are varied and the corresponding changes in structural, morphological and optical properties were reported. The structure, orientation, surface morphology and optical properties of the ZnO nanorods were investigated by XRD, SEM & UV studies. The influence of growth and annealing temperatures on structural and optical properties were reported.

Annealing Effect on the Surface Morphology and Photoluminescence Properties of ZnO Nanorod Prepared by Catalytic-Immersion Method Grown on Si and Au/Si Substrate

ZnO nanorods were prepared by immersion method deposited onto Silicon (Si) and gold-seeded Si (Au/Si) substrate. The annealing temperatures were varied from 400, 500 and 600 °C. The effect of annealing temperature on the surface morphology and photoluminescence characteristics was investigated. The samples were characterized by Field Emission Scanning Electron Microscope (FESEM) to study their morphology and structural properties while the optical properties were characterized at room temperature using Photoluminescence Spectroscope. The shape of ZnO showed growth of nanorods with hexagonal shape. As the annealing temperature increased, the morphology study indicates that particle size of ZnO decreased while the crystallinity increases. The structures has high surface area, is a potential metal oxide nanostructures to be develop for optoelectronic devices and chemical sensors.

The Effect of Deposition Time on the Structural Properties of ZnO Nanorods Prepared by Sol-Gel Immersion Method

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.

Optical and Structural Properties of ZnO Nanorods Prepared by Chemical Bath Deposition Method

Abstract The Chemical bath deposition method was used for the preparation of ZnO nanorods and their optical and structural properties were studied. ZnO seed layer thin films were prepared by chemical bath deposition technique on to well cleaned glass substrates. ZnO seed-coated glass substrates were immersed in aqueous solution of zinc nitrate and hexamethylenetetramine (HMT) on 1:10 molar concentration at 90°C for 4 hours and annealed at different temperatures. The effect of annealing temperatures on the surface morphology and optical properties of the films was studied. The structure of the ZnO nano rod was studied by X-ray diffractometer and scanning electron microscopy. The optical property was studied by UV-Vis spectroscopy and photoluminescence spectroscopy. Experimental results have shown that prepared ZnO nanorods by this method have higher photoluminescence

Effect of the surface-plasmon–exciton coupling and charge transfer process on the photoluminescence of metal–semiconductor nanostructures

The effect of direct metal coating on the photoluminescence (PL) properties of ZnO nanorods (NRs) has been investigated in detail in this work. The direct coating of Ag nanoparticles (NPs) induces remarkable enhancement of the surface exciton (SX) emissions from the ZnO NRs. Meanwhile, the charge transfer process between ZnO and Ag also leads to notable increment of blue and violet emissions from Zn interstitial defects. A thin SiO2 blocking layer inserted between the ZnO and Ag has been demonstrated to be able to efficiently suppress the defect emission enhancement caused by the direct contact of metal-semiconductor, without weakening the surface-plasmon-exciton coupling effect. A theoretical model considering the type of contacts formed between metals, ZnO and blocking layer is proposed to interpret the change of the PL spectra.

Raman and Photoluminescence Properties of ZnO Nanorods with Wurtzite Structure

Raman, resonant Raman and photoluminescence (PL) properties of ZnO nanorods that produced by simple solution chemical process are reported in this paper. The transmission electron microscopy measurements show that the obtained ZnO nanorods have well-proportioned distribution with diameters about 30 nm, and the maximal lengths up to more than 2.2 μm. The micro-Raman and resonant Raman spectrum of nanorods show the obvious differences from that of the commercial bulk phase ZnO samples. The PL with intense UV emission indicates the good quality of the obtained ZnO nanorods.

Surface modification effect on photoluminescence of individual ZnO nanorods with different diameters

Optical properties of Al2O3 coated individual ZnO nanorods (NRs) with different diameters were studied by confocal micro-photoluminescence spectroscopy. The one-dimensional ZnO/Al2O3 core-shell NRs showed enhanced near band-edge emission compared with the same ZnO NRs before Al2O3 coating at room temperature. Besides, the relative intensity of the deep-level emission with respect to the near band-edge emission was reduced. A model was proposed to explain these spectral changes. For ZnO NRs with diameters above 360 nm, a multi-mode behavior resulting from whispering gallery resonance was observed. In addition, selective enhancement or quenching of different whispering gallery modes in ultraviolet (UV) emission was observed after Al2O3 coating at room temperature, which is due to the larger refractive index of Al2O3 compared with air. We proposed a model to explain these spectral changes as well. By comparing the optical properties before and after surface coating, our results suggest that surface coating of an Al2O3 layer is an effective way to tailor the optical properties of ZnO NRs.