Fabrication Of Zinc Oxide Research Articles

P-n homojunction based on Bi doped p-type ZnO and undoped n-type ZnO for optoelectronic application in yellow-red region of visible spectrum

Fabrication of zinc oxide (ZnO) based optoelectronic devices requires stable and reproducible p-type nanostructures. Keeping this fact in view, high-quality Bismuth (Bi) doped p-type ZnO thin films have been deposited on the n-Si substrate using sol-gel spin coating technique. Hall effect and hot point probe measurement confirm that deposited Bi doped ZnO film has p-type conductivity with a resistivity of 0.82 Ω-cm, carrier concentration of 1.1 × 1018 cm−3 and mobility of 6.9 cm2/ V-s at room temperature. A p-n homojunction has been fabricated by making use of this p-type ZnO and intrinsic n-type ZnO. The I-V characteristics of the fabricated p-n junction clearly show the rectifying nature. PL analysis reveals that the fabricated device exhibits deep level emission in yellow and red emission bands ascertaining its potential application in optoelectronics.

High-speed observation of semiconductor microsphere generation by laser ablation in the air

We have succeeded in fabricating zinc oxide (ZnO) microsphere by laser ablation in the air and demonstrated ultraviolet whispering gallery mode lasing from an optically pumped ZnO microsphere. However, fabricated microspheres could not be controlled in size, and ejection direction of microsphere was random, because the generation mechanism was attributed to the droplet ejection by laser ablation. In this report, the effect of pulse duration on microsphere generation was investigated, and we introduced optical vortex to control the size and the ejection direction of droplets. The behavior of ablated target was visualized using a high-speed camera. As a result of time-resolved observation, it was found that many ZnO microspheres can be efficiency generated by the long pulse laser irradiation. In addition, it was observed that droplets were scattered randomly by Gaussian beam irradiation. In the case of optical vortex irradiation, straight flight of the droplet was achieved. Furthermore, the size of droplets changed with pulse energy and ablation spot size with optical vortex. From these results, controlled fabrication of ZnO microspheres is expected with optical vortex laser ablation.

Design and Fabrication of Zinc Oxide and Polyethylene Terephthalate Based Nano-Generator for Sensing Applications

Design and Fabrication of Zinc Oxide and Polyethylene Terephthalate Based Nano-Generator for Sensing Applications

Structural, optical, and electrical properties of ZnO nanofilms deposited over PS substrate

The research successfully revealed the fabrication of zinc oxide (ZnO) nanofilms with hexagonal (002) structure grown on porous silicon (PS) substrate using chemical bath deposition method. Their structural, optical, and electric characteristics were investigated through X-ray diffraction, field emission scanning electron microscopy (FESEM), and photoluminescence spectroscopy. FESEM showed that ZnO nanofilms were formed on top and inside the pores of PS substrate with hexagonal shape. The strong ultraviolet emission of ZnO nanofilms is also presented at ∼383 nm near the band edge energy levels which can be applied in semiconductor device both photoelectron devices and chemical sensors. In addition, current–voltage (I–V) characteristics revealed that the current level for ZnO nanofilms was about three times larger than for PS layer.

Preparation and Characterization of Zinc Oxide Based Photoanode for Dye-sensitized Solar Cell using Delonix Regia Natural Dye Extract

<p>As of late, research on the fabrication of natural dye-sensitized solar cells has been growing tremendously, largely due to its low cost and environmentally friendly nature. We have fabricated Zinc Oxide (ZnO) based Dye-sensitized Solar Cell (DSSC) using Delonix Regia, locally known as the Gulmohar flower natural dye extract. Zinc Oxide nanostructure films were allowed to grow on Fluorine-doped Tin Oxide (FTO) substrates via hydrothermal process. The seed layer for this was prepared by the spin coating method. The ZnO film’s structure, topology, and optical properties were then studied using X-ray Diffraction (XRD), an Atomic Force Microscope (AFM) and an Ultraviolet Visible (UV-Vis) Spectrophotometer respectively. The X-ray results showed the hexagonal system structure of ZnO oriented along (101) planes. The effect of ethylene glycol on the structural property of ZnO film was also studied. The current voltage curve of DSSC showed the open circuit voltage and short circuit current of 360 mV and 80 μA respectively.</p><p><strong>Journal of Nepal Physical Society</strong><br />Volume 4, Issue 1, February 2017, Page: 1-6</p>

Fabrication of Zinc Oxide from Zinc Dust and Its Characterization

Fabrication of Zinc Oxide from Zinc Dust and Its Characterization

Fabrication of zinc oxide/ polyaniline (ZnO/PANI) heterojunction and its characterisation at room temperature

We report the formation of a diode like ZnO/PANI heterojunction structure by RF sputtering technique with a high rectification ratio in the laboratory. The diode parameters obtained from the I-V data using the established methods of Cheung and Norde's function, based on the thermionic emission model of diode, agrees with each other. The current mechanism in the diode was ohmic at lower voltages (at voltages less than 2.8V) where as space charge limited current (SCLC) dominates at higher voltage (above 3.5V). The measured I-V characteristics remain the same under bending conditions also. This indicates that this heterojunction could be exploited positively in flexible electronics.

Toxicity on Dengue Mosquito Vectors Through Myristica fragrans-Synthesized Zinc Oxide Nanorods, and Their Cytotoxic Effects on Liver Cancer Cells (HepG2)

Dengue is an arbovirus mainly vectored by Aedes mosquitoes. Its prevention and control depends to effective vector control measures. Cancer causes millions of death every year. Most of the anticancer drugs have high toxicity and low specificity of action, leading to systemic toxicity and severe side effects. Thus, the development of effective tools is a priority. We fabricated zinc oxide nanoparticles using the Myristica fragrans extract as a reducing and stabilizing agent. Nanoparticles were studied using UV–vis spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential, dynamic light scattering, energy dispersive X-ray analysis, field emission scanning electron microscopy and transmission electron microscopy. ZnO nanorods were highly effective against A. aegypti young instars, with LC50 ranging from 3.44 (larva I) to 14.63 ppm (pupa). Nanorods showed adult LC50 of 15.004 ppm. ZnO nanorods exhibited dose-dependent cytotoxicity against human hepato-cancer cells (HepG2). After 48 and 24 h of incubation, the IC50 were 20 and 22 μg/ml, respectively. Nanorods triggered the induction of apoptosis. Overall, this study highlights that the possibility to employ M. fragrans-synthesized ZnO nanorods in mosquito control, as well as in the development of novel chemotherapeutic agents with reduced systemic toxicity.

7-Octenyltrichrolosilane/trimethyaluminum hybrid dielectrics fabricated by molecular-atomic layer deposition on ZnO thin film transistors

We demonstrate the fabrication of 7-octenytrichlorosilane (7-OTS)/trimethylaluminum (TMA) organic–inorganic hybrid films using molecular-atomic layer deposition (MALD). The properties of 7-OTS/TMA hybrid films are extensively investigated using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and electrical measurements. Our results suggest that uniform and smooth amorphous hybrid thin films with excellent insulating properties are obtained using the MALD process. Films have a relatively high dielectric constant of approximately 5.0 and low leakage current density. We fabricate zinc oxide (ZnO) based thin film transistors (TFTs) using 7-OTS/TMA hybrid material as a back gate dielectric with the top ZnO channel layer deposited in-situ via MALD. The ZnO TFTs exhibit a field effect mobility of approximately 0.43 cm2 V−1 s−1, a threshold voltage of approximately 1 V, and an on/off ratio of approximately 103 under low voltage operation (from −3 to 9 V). This work demonstrates an organic–inorganic hybrid gate dielectric material potentially useful in flexible electronics application.

Electrochemical characterisations of ZnO nanowires for dye-sensitised solar cells

Dye-sensitised solar cells (DSSCs) using fluorine-doped tin oxide (FTO) supporting substrate have been developed for fabricating zinc oxide (ZnO) nanowires film electrodes (anode). The ZnO nanowires were prepared by hydrothermal synthesis by varying process parameters such as the concentration of the seeding solution and the number of seed layers. The obtained electrodes were characterised by electrochemical impedance spectroscopy (EIS). The effects of seeds and dye solution soaking time were studied. The results show that charge transfer resistance (Rct) decreases with increasing the number of seed layers, and with the dye solution soaking time, due to an increase of both the specific surface area and the coverage by the dye, respectively. In addition, it was found that dye solution soaking for 16h maintains Rct at a low value (when measured under illumination) 72h after assembling the DSSC. This indicates that there is no dye desorption after this time.

Reduced-temperature solution-processed transparent oxide low-voltage-operable field-effect transistors

Abstract

Sponge-Templated Macroporous Graphene Network for Piezoelectric ZnO Nanogenerator.

We report a simple approach to fabricate zinc oxide (ZnO) nanowire based electricity generators on three-dimensional (3D) graphene networks by utilizing a commercial polyurethane (PU) sponge as a structural template. Here, a 3D network of graphene oxide is deposited from solution on the template and then is chemically reduced. Following steps of ZnO nanowire growth, polydimethylsiloxane (PDMS) backfilling and electrode lamination completes the fabrication processes. When compared to conventional generators with 2D planar geometry, the sponge template provides a 3D structure that has a potential to increase power density per unit area. The modified one-pot ZnO synthesis method allows the whole process to be inexpensive and environmentally benign. The nanogenerator yields an open circuit voltage of ∼0.5 V and short circuit current density of ∼2 μA/cm(2), while the output was found to be consistent after ∼3000 cycles. Finite element analysis of stress distribution showed that external stress is concentrated to deform ZnO nanowires by orders of magnitude compared to surrounding PU and PDMS, in agreement with our experiment. It is shown that the backfilled PDMS plays a crucial role for the stress concentration, which leads to an efficient electricity generation.

Optimizing Folded Silicon Thin-Film Solar Cells on ZnO Honeycomb Electrodes

A promising approach for low-cost nanostructured thin-film solar cells with enhanced absorption is the fabrication of zinc oxide (ZnO) honeycomb electrodes in a combined bottom-up process of nanosphere lithography and electrochemical deposition. To optimize the honeycomb structures, we investigate thin hydrogenated amorphous silicon (a-Si:H) solar cells (with 100 nm absorber thickness) on honeycomb electrodes with different periodicities in optical and electrical simulations; whereas the electrical performance is not significantly affected with changing periodicity, the short-circuit current density is reduced for increasing honeycomb diameter due to increased parasitic absorption of the electrochemically deposited ZnO. Furthermore, we demonstrate that for micromorph tandem solar cells with an intrinsic layer thickness of hydrogenated microcrystalline silicon (μc-Si:H) of >500 nm, a focusing effect occurs, which leads to a strong enhancement in the quantum efficiency in the microcrystalline bottom solar cell.

Effect of calcination temperature on the properties of ZnO nanoparticles

ZnO nanoparticles have been synthesized by sol–gel technique using zinc acetate dihydrate and diethanolamine as the precursor materials. The effects of calcination temperatures, i.e., 300, 500, 650, 700, and 750 °C, on the crystallinity, optical properties, and size of fabricated zinc oxide nanoparticles were investigated. X-ray diffraction (XRD) analysis reveals the hexagonal wurtzite structure. Crystallite size estimated by XRD data is about 20 nm and increased by increasing calcination temperature. Particle size was supported by particle size analyzer. Fourier transform infrared spectroscopy was used to classify molecular species through thermal decomposition. Its spectra show the ZnO nanoparticles formation in the wave number range 400–500 cm−1 while bonding was eliminated by heating process. Differential scanning calorimetry–thermal gravimetric analysis/differential thermal analysis curves indicate weight loss by thermal effect. Precursor decomposes at ~250 °C and mass loss took place from 100 to 500 °C. Ultraviolet–visible (UV–Vis) absorption was utilized to analyze the optical properties of samples. It is seen that the band gap value shows only very slight increase with increasing calcination temperature. Best band gap of 3.08 eV was measured for the sample prepared without calcination.

Synthesis and characterization of zinc oxide (ZnO) filled glass fiber reinforced polyester composites

This study aims at fabrication of zinc oxide (ZnO) filled glass fiber reinforced polyester (GFRP) composites with varying concentrations of filler and investigation of their mechanical and thermal behavior. In this study, ZnO was dispersed in polyester, and laminates were fabricated by hand lay-up technique followed by compression molding. Mechanical properties were determined by flexural strength analysis, impact strength and hardness testing whereas thermal stability by thermogravimetric analysis (TGA). Flexural strength of 3wt.% ZnO filled GFRP composite was improved significantly (up to 62.12%) in comparison to unfilled composite. Hardness, impact strength and thermal stability have also been found increased gradually with increase in ZnO loading.

A perfectly linear trinuclear zinc–Schiff base complex: Synthesis, luminescence property and photocatalytic activity of zinc oxide nanoparticle

A perfectly linear trinuclear zinc(II) complex [Zn3L2(μ-O2CCH3)2] (1) containing a (N,O)-donor Schiff base ligand, (H2L=N,N′-bis(salicyaldehydene)-1,3-diaminopropan-2-ol) has been synthesized and characterized by single crystal X-ray diffraction study. The X-ray crystal structure of 1 contains three zinc(II) centers which are inter-connected through μ2-phenolato and μ-acetato bridges. The terminal zinc centers are in square pyramid geometry and central zinc ion is in distorted octahedral coordination geometry. Both H2L and 1 exhibit good fluorescence properties in solution. 1 has been used as a precursor to fabricate zinc oxide nanoparticles (ZnONPs) by pyrolytic method. ZnONP has been characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), FT-IR spectroscopy and UV–Vis spectroscopy techniques. ZnONP has been employed as photocatalytic agent to degrade the organic dye, viz. Methylene blue under visible light and by exposing to visible light for 1h, ZnONP degraded methylene blue dye nearly 80%.

Fabrication and characterization of spherical micro semiconductor crystals by laser ablation method

We have been establishing the technique of fabricating spherical semiconductor microcrystals with suitable diameters for whispering gallery mode (WGM) lasing. Concretely, semiconductor microspheres were synthesized by ablating various semiconductor-sintered targets with focused pulsed laser at high fluences. In this report, dependences of fabricated zinc oxide (ZnO) microstructures on laser wavelengths were investigated. Lasing characteristics and photoluminescence of ZnO microspheres were determined, and photoluminescence of Sb-doped ZnO microspheres were determined. Additionally, it was also found that Sb-doped ZnO and aluminum nitride microspheres can be similarly synthesized. By developing this method, which does not require complex processing, it is expected that efforts in the application of WGM lasing are accelerated in many kinds of semiconductors.

Structural Properties of Zinc Oxide Nanorods Grown on Al-Doped Zinc Oxide Seed Layer and Their Applications in Dye-Sensitized Solar Cells.

We fabricated zinc oxide (ZnO) nanorods (NRs) with Al-doped ZnO (AZO) seed layers and dye-sensitized solar cells (DSSCs) employed the ZnO NRs between a TiO2 photoelectrode and a fluorine-doped SnO2 (FTO) electrode. The growth rate of the NRs was strongly dependent on the seed layer conditions, i.e., thickness, Al dopant and annealing temperature. Attaining a large particle size with a high crystallinity of the seed layer was vital to the well-aligned growth of the NRs. However, the growth was less related to the substrate material (glass and FTO coated glass). With optimized ZnO NRs, the DSSCs exhibited remarkably enhanced photovoltaic performance, because of the increase of dye absorption and fast carrier transfer, which, in turn, led to improved efficiency. The cell with the ZnO NRs grown on an AZO seed layer annealed at 350 °C showed a short-circuit current density (JSC) of 12.56 mA/cm2, an open-circuit voltage (VOC) of 0.70 V, a fill factor (FF) of 0.59 and a power conversion efficiency (PCE, η) of 5.20% under air mass 1.5 global (AM 1.5G) illumination of 100 mW/cm2.

Aqueous zinc ammine complex for solution-processed ZnO semiconductors in thin film transistors

We fabricated zinc oxide (ZnO) TFTs using a zinc ammine complex with various zinc oxide sources such as ZnO, intrinsic Zn(OH)2, and precipitated Zn(OH)2. From the analyses of the reaction mechanism, surface morphology, crystal structure, and oxygen vacancy in the ZnO films, we confirmed the same intermediate in ZnO semiconductor films irrespective of the type of zinc oxide source in the zinc ammine complex precursor. The results showed the analogous value of the average field effect mobility, on/off current ratio, and turn-on voltage in all solution-processed ZnO TFTs. In conclusion, we confirmed that directly dissolving pristine ZnO into ammonia water is the most efficient method for preparing the ZnO semiconductor precursor, the zinc ammine complex, for low-temperature, solution-processed, and high performance ZnO TFTs.

Formulation of Synthesized Zinc Oxide Nanopowder into Hybrid Beads for Dye Separation

The sol‐gel prepared zinc oxide nanopowder was immobilized onto alginate‐polyvinyl alcohol polymer blend to fabricate novel biocomposite beads. Various physicochemical characterization techniques have been utilized to identify the crystalline, morphological, and chemical structures of both the fabricated zinc oxide hybrid beads and their corresponding zinc oxide nanopowder. The thermal stability investigations demonstrate that ZnO nanopowder stability dramatically decreased with its immobilization into the polymeric alginate and PVA matrix. The formulated beads had very strong mechanical strength and they are difficult to be broken up to 1500 rpm. Moreover, these hybrid beads are chemically stable at the acidic media (pH < 7) especially within the pH range of 2–7. Finally, the applicability of the formulated ZnO hybrid beads for C.I. basic blue 41 (BB41) decolorization from aqueous solution was examined.