Preparation Of ZnO Thin Films Research Articles

Effect of deposition time on properties of the ZnO by USD Method

This investigation aims to improve the properties of 304 L stainless steel (SS) substrates for use in corrosion, mechanical, and biomedical applications by depositing ZnO thin films. The ultrasonic spraying technique was used to prepare ZnO thin films with depositional times of 1, 4, and 9 minutes. XRD and Raman studied the surface characteristics of ZnO samples. XRD analysis revealed a hexagonal structure with an average crystallite size of 22 nm for ZnO. Indentation nano measurements indicated an increase in the hardness of the films examined. To determine the type of conductivity and estimate the charge carrier density, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis were performed. The thin film deposited for 9 minutes was found to be the most effective in improving corrosion resistance.

Structural and Optical Characteristics of Multilayer ZnO Nanorod:TiO2 by DC Magnetron Sputtering for Dye Sensitized Solar Cell (DSSC) Application

The development of Dye-Sensitized Solar Cell (DSSC) technology by utilizing various semiconductors has attracted attention. Among all types of semiconductors, the nanostructure of ZnO is selected due to their unique electrical properties and ease of preparation in various morphologies, and it has been considered a promising material to be applied in DSSC. In this research, the DC magnetron sputtering method was used to prepare ZnO thin films as an efficient alternative to press the charge recombination process that occurs in TiO2-based DSSC. Different thicknesses of TiO2 layers on the FTO conductive glass substrate were made through various sputtering deposition times, while the ZnO nanorod layers were made with a single layer using the hydrothermal method. We used XRD, SEM, UV-Vis, I-V meter, and EIS analysis. Based on these characterization we concluded that multilayer ZnO nanorod:TiO2 coating with a sputtering time of 60 minutes resulted the best performance of DSSC with an efficiency of 0.27%.

P‐12.8: A Vertical Alignment Technology of Proessing ZnO Sputtered with Ozone Applied on Liquid Crystal on Silicon Display Devices

The vertical alignment technology by processing sputtered ZnO film for LCD with ozone is proposed in this paper. The prepared ZnO thin films were treated with ozone in the ultraviolet cleaning machine through polarizer. The wettability of the treated ZnO films switched to hydrophobicity, reaching a contact angle of 92°. With the prepared ZnO film as the alignment layer in the transmissive LCD cell, the vertical alignment (VA) can be realized. The results demonstrated that the test cells not only possessed the photo‐electronic characteristics of traditional VA liquid crystal cells but also had a smaller threshold voltage of 1.95V. In addition, the ZnO films are applied into character display successfully since the VA test cell has a high contrast ratio.

In-situ solution processed zinc Oxide as electron transport layer for High-performance perovskite Light-emitting diodes

As an alternative method of the electron transport layer (ETL) of Zinc Oxide nanoparticles, an in-situ solution process was developed to prepare ZnO thin films for manufacturing perovskite light-emitting diodes (PeLEDs). After optimizing the processing conditions, the band energy and electron mobility are adjusted appropriately, which shows advantages to balance the carrier injection in PeLEDs. The near-infrared PeLEDs with ZnO film prepared by in-situ method demonstrated external quantum efficiency of 22%, which is compatible with their counterpart using ZnO nanoparticles. Our report provides a feasible strategy for the low-cost fabrication of PeLEDs with high performance.

Study the structural and Optical properties of ZnO thin film

This research included preparation of ZnO thin films from Zinc acetate solution (Zn(CH3COO)22H2O). on glass substrate with dimension (2.5cmx2.5cmx0.1cm) using chemical spray pyrolysis method composed with (0.2M). The structural properties were characterized by X-Ray diffraction (XRD), Atomic force microscope (AFM), Scanning electron microscope (SEM) and Energy dispersive of X-Ray (EDX). The film grown have a polycrystalline wurtizte structure it can be seen that the highest texture coefficient was in (002) plane. So (AFM) measurement show that the roughness average (1.51nm), root mean square (RMS = 1.75nm) and dimeter average (108.96nm). The optical properties were characterized by (UV- Visible) and showed that higher transmittance about (97%) and optical Energy gab (Eg=3.28 eV).

Effect of Oxygen Flow Rate on PECVD Prepared ZnO Thin Films Physical Properties: Experiments Associated with DFT Calculations

Effect of Oxygen Flow Rate on PECVD Prepared ZnO Thin Films Physical Properties: Experiments Associated with DFT Calculations

Preparation of ZnO compact layer using vacuum ultraviolet for dye-sensitized solar cells

Vacuum ultraviolet (VUV) light with a wavelength of 172 nm has the capacity to convert the oxygen contained metal organic precursor into metal oxide. Here, zinc acetate precursor thin film is directly converted into ZnO thin film by the irradiation of 172 nm VUV light rather than the high temperature sintering. The converting processes were demonstrated by the measurements of FTIR, XRD, SEM and XPS. And then the effect of irradiating time on the morphology, thickness and transparence of the prepared ZnO thin films was discussed. The ZnO thin film was further used as the compact layer in the photoelectrode of dye-sensitized solar cell (DSSC) to suppress the recombination processes of photogenerated electrons on the conducting glass electrode. For the different irradiation times, the photoelectric conversion efficiency of DSSC based on the compact layer prepared by the irradiation for 30 min is the highest reaching 10.27%, which is also higher than that of DSSCs without the compact layer and even with the compact layer prepared by the high temperature sintering. The uniform, dense, pinhole-free and amorphous ZnO thin film on the conducting glass substrate can be successfully prepared using the VUV irradiation technology for the compact layer of DSSCs.

Impact of improvements in ZnO thin film solution process on ZnO/Cu2O solar cell performance

ZnO semiconductor is an ideal n-type window material for a solar cell owing to both the abundance of zinc in nature and its stable structure. The preparation of ZnO thin films with proper crystallinity is still possible only with expensive production methods. It is challenging to grow high quality ZnO thin film by the sol-gel spin coating method which is simple and low-cost. Generally, ZnO thin films prepared by spin coating method demonstrate poor crystallinity properties. The crystallinity of ZnO and hence the heterojunction efficiency can be enhanced, by simply improving the solution process. Additionally, the comparison of solar cell efficiency based on the quality of ZnO thin film prepared by the spin coating method in the literature is still a deficiency. Therefore, in this study, the semiconductor properties of ZnO thin films prepared by a spin coating method using the improved solution process compared to our previous study were investigated. The p-Cu 2 O thin film electrodeposition was achieved by our novel low-cost two-electrode cell utilizing a simple DC power supply and microammeter. The semiconductor properties of ZnO thin films and their impacts on ZnO/Cu 2 O bilayer heterojunction efficiency were elaborated by means of structural, optoelectronic, and I–V characterizations. The crystal quality of ZnO has been significantly improved, and a large increase in the output current and voltage of the fabricated solar cells has been achieved. • The preparation of ZnO thin films with proper crystallinity require expensive vacuum based equipment. • It is challenging to grow high quality ZnO thin film by sol-gel spin coating method which is simple and low cost. • By simply improving the solution process, the ZnO/Cu 2 O solar cell output voltage and current can be enhanced. • Investigation of various combination of ZnO/Cu 2 O based heterostructures.

Fabrication and Study of ZnO thin Films using Thermal Evaporation Technique

In this study, thin film Zinc oxide (ZnO) deposited by thermal evaporation techniques on unheated glass substrates. The findings of X-ray diffraction (XRD) show that the ZnO films are amorphous before annealing. The subsequent diffraction patterns demonstrate that the films crystalline into polycrystalline mixed Tetragonal α-ZnO compounds and Orthorhombic s-ZnO compounds. Atomic power microscope (AFM) shows that the ZnO films are of a large homogeneous surface. The median crystallite size is calculated from XRD data, which are increased for all thickness with an increasing ringing temperature and are less than the AFM data. The findings of the optical properties show that with rising annealing temperature for all thicknesses, the transmittance decreases. ZnO film shows transmittance that exceeds 95% in the IR radiation area of the spectrum at the lower thickness of 60 nm annealed at 523 K for 2 hr, but decreases to 87% percent with increasing annealing temperatures, although ZnO films with thicknesses of 130 nm annealed at 723 K for 2 hr have a transmittance of 94 % and 88 % in the IR region, but decreases High transmission in the IR area reveals that ZnO films are good materials for agricultural applications. All the prepared ZnO-thin films were n-type semiconductors and it is known that the concentration of the carriers (n) and the conductivity (σ) increased with an ever-greater annealing temperature, while their mobility (μ) and resistivity (ρ) is reduced with an increase in the annealing temperature.

The efficiency of natural dyes-based dye sensitised solar cells

ZnO/natural dyes solar cell (DSSC) had been successfully synthesised. The preparation of ZnO thin films was carried out on an indium thin oxide (ITO) glass substrate using the sol-gel spin coating method. The natural dyes were extracted from tamarillo, red dragon fruit, red spinach, boat lily flower and purple hibiscus flower, each cut into small pieces and put into a beaker glass. The sample was then further crushed with a mortar and then milled until it became soft. The extracted dyes were heated for 5 h and diluted with distilled water to obtain dye solutions. The DSSC structure was formed by glueing together the ZnO/dye and a platinum plat by using Surlyn. The ZnO/dye and platinum were successively used as a working electrode and counter electrode. The Surlyn functioned as glue and conductor. The DSSC structure then put on a hot plate with a temperature of 70°C–80°C to enable Surlyn pasted perfectly. Further, electrolyte liquid was injected into the ZnO/dye-platinum structure. The ZnO thin films were characterised by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and UV-Vis spectrometer. The ZnO/natural dyes thin films were formed by dipping the ZnO thin film into natural dyes solution with the ZnO thin films facing up for 24 h to let the dyes adsorbed by the film. DSSC efficiencies were measured by a simple circuit consisting of DSSC, both analogue and digital multimeters. The results showed that the ZnO crystal structure was of wurtzite hexagonal shape with a crystallite size of 27.3 nm, high-density granules with narrow inter granules boundary, and the band-gap was 3.25 eV. The maximum and minimum values of the sensitisers were from red spinach and red dragon fruit which were 3.30 a.u and 2.50 a.u. The DSSC can convert solar energy to electrical energy with power and efficiency of consecutively of 0.101 W cm–2 and 0.278%.

Absorbance dependence of ZnO thin films on post-heating temperature

We have prepared ZnO thin films on indium tin oxide (ITO) glasses using dip-coating at room temperature. Post-heating has been performed by different temperatures i.e. 450 °C, 500 °C, 550 °C, and 600 °C under atmosphere ambient. The effect of post-heating temperature on the structural properties and absorbance of ZnO thin films have been investigated. Structurally, we observed ZnO thin films under a post-heating temperature of 450 °C, 500 °C, and 550 °C have polycrystalline hexagonal wurtzite structure. Meanwhile, at the temperature of 600 °C, it has an amorphous structure. Optical absorbance spectra of ZnO thin films confirmed that amorphous structure has the highest intensity compared to polycrystalline hexagonal wurtzite structure.

Fabrication and characterization of ZnO/Cu2O heterostructures for solar cells applications

Abstract Zinc oxide and cuprous oxide thin films are environmentally friendly and low-cost semiconductors and have various optoelectronic applications. The overall cost of the heterostructures they form can also be reduced via economic fabrication methods. ZnO and Cu2O thin films can be deposit under normal laboratory conditions via spin coating and electrodeposition methods. However, the main concerns of the low-cost methods are the growth of pure Cu2O and efficient interface between the films. On the other hand, it is still worth exploiting the low-cost spin coating and electrodeposition methods due to their efficient thin film growth potential. In this study, the one-step spin coating method was employed to prepare ZnO thin films. The electrodeposition of Cu2O thin film was achieved via developed a simple two electrodes cell. The structural, morphological, optical, and electrical measurements show that p-type Cu2O thin films were successfully deposited with our system. Although the open circuit voltage of the prepared heterojunction solar cell devices is quite low, the methods here we apply and the conditions have the potential to fabricate a solar cell. Open circuit voltage and thus efficiency will increase by improving interfaces with chemical methods and more effective annealing.

Bandgap Tuning and Blue-Green Band Emissions of Sol-Gel Synthesized ZnO Films by High Cu Doping.

The present research focuses on the preparation of ZnO thin films both undoped and doped with varying Cu concentrations (0.0%, 0.8%, 3.0%, 5.0%, 10.0% and 20.0%) using sol-gel spin coating technique. The optical bandgap (Eg) for undoped films is recorded as 3.239 eV and shows a little increase to 3.248 eV when it is doped with 0.8% Cu concentration whereas further increase of Cu doping concentration, it is decreased from 3.248 eV to 3.107 eV for 20% Cu. The EU (Urbach Energy) is improved with the enhancement of Cu doping concentration. Ultraviolet (UV) and bluegreen band emissions are noticed from PL (photoluminescence) spectra. The UV peak intensities are diminished with increasing Cu doping concentration while the blue peaks intensities are amplified. These results illustrate that ZnO films doped with Cu meet the requirement for applications in different blue emission devices.

Controlling electrical and optical properties of zinc oxide thin films grown by thermal atomic layer deposition with oxygen gas

The preparation of ZnO thin films with controlled electrical resistivity and optical properties is often challenged by the presence of defects, such as oxygen vacancies or interstitial zinc. Here, we investigate the material properties of ZnO polycrystalline thin films prepared by thermal Atomic Layer Deposition (ALD) with the presence of molecular oxygen pulsing during the growth. By means of structural, electrical and optical characterizations, we identify key growth parameters of this unusual ALD process. Unexpectedly, the influence of oxygen molecules on the crystallography, microstructure and morphology of ZnO films is significant from hundred-nanometers to micrometer thick film. The electrical resistivity of the films grown with oxygen gas shows a dramatic increase from 3 to 4 orders of magnitude. Additionally, photoluminescence measurements reveal that deep-level emissions caused by defects located deep in the band gap can be reduced by applying an adequate pulsing of oxygen gas during the process. Finally, we conclude with a discussion about the degree of consistency between the chemical composition, the inner strain and the optical and electrical properties of the films obtained with the different thermodynamic parameters of growth. Several hypotheses are discussed in order to understand the dominance of (002) orientation in the presence of oxygen during the ALD growth process.

Structural and optical properties of ZnO thin film prepared by sol-gel spin coating

Abstract Zinc oxide (ZnO) thin films were deposited on Si (1 0 0) and glass substrates by sol-gel spin coating technique. Zinc acetate dihydrate, monoethanolamine and isopropanol were used as the sources for precursor solution and the resulting gel was used for the preparation of ZnO thin films. The films were annealed at different temperatures (100 °C to 500 °C) and the effect of annealing on the structural and optical properties was investigated. X-ray diffraction (XRD) and UV-Vis spectroscopy were used for the analysis of the films. The XRD results indicated the polycrystalline hexagonal structure of the ZnO films with (0 0 2) orientation. The optical properties of the films were studied using UV-Vis spectrophotometer in the wavelength range of 190 – 1100 nm. The optical characterization of the ZnO thin films showed the high transmittance of ~90 % for the films annealed at 400 °C. The films showed the absorbance ~360 – 390 nm and bandgap values of 3.40 – 3.10 eV, depending on the annealing temperature of the films.

Analysis of a plasma-assisted reactive evaporation process for preparation of ZnO thin films: Modeling and experimentation

This paper focuses on modeling and simulation of a plasma-assisted reactive evaporation process. A dimensional unsteady-state model consisting of six nonlinear parabolic partial differential equations which account for the diffusive and convective mass transfer, bulk and surface reactions, non-uniform fluid flow, and plasma electron density profiles is developed. The equations are spatially discretized using finite difference methods and then numerically solved. The simulation results are validated by comparison with a commercial simulation software that computes similar equation systems. To validate the model, experimental measurements of film thickness are carried out on ZnO films deposited by plasma-assisted reactive evaporation. After 130 min of deposition time and deposition rate around 6 nm/min, the simulated results and the experimental measurements exhibit a good agreement (770 nm and 750 nm respectively), just around 2.59% discrepancy in the final thin film thickness, hence showing the high accuracy of the developed model.

Facile preparation of ZnO nanostructured thin films via oblique angle ultrasonic mist vapor deposition (OA-UMVD): a systematic investigation

Ultrasonic mist vapor deposition (UMVD) is a widely used facile technique to prepare ZnO thin films. The surface properties of prepared thin films can be tuned via easily controllable UMVD deposition parameters. Herein, we utilized an oblique angle (OA) geometry in UMVD system named as OA-UMVD. The angle between incident flow and substrate (θs) was changed from 0° to 45°. Alteration of θs as well as substrate temperature (Ts) resulted in the deposition of ZnO thin films with different morphologies. For mild nozzle–substrate distance (D = 3 cm), fine vertical ZnO nanosheets with length of 123 nm and thickness of 23 nm were obtained for low Ts (330 °C) and small θs (≈ 0°). By increasing both Ts and θs, ZnO nanorods gradually appeared on the surface. Both nozzle–substrate distance (D) and Ts showed similar effect on deposition rate (Rd), and Rd decreased by increase of D and Ts, while deposition rate increased for larger θs. Confocal microscopy results revealed that using low Ts (330 °C), short distance (D = 1.5 cm) and large θs (45°) resulted in high macroscopic surface roughness (MRs) of 98 nm, while high Ts (500 °C), long D (5 cm) and small θs (≈ 0○) created compact and smooth surface with low MRs of 5 nm, in accordance with transmittance results. The ZnO wurtzite crystal structure was approved via X-ray diffraction patterns. The crystallite size in the layers was affected only by Ts, and θs had no significant effect on the layers’ crystallinity. Obtaining different ZnO nanostructures with different MRs via easily and accurately controllable growth parameters is a great advantage for our employed OA-UMVD system, which could be used to prepare ZnO thin films with desired morphologies for widespread application fields.

Synthesis and characterization of Ca doped ZnO thin films by sol–gel method

ZnO thin films were synthesized using sol–gel method at 0.25 and 0.5 M molarity concentration. Moreover, the obtained thin films were Calcium-doped with 1 and 5 at% concentration. In order to investigate the structural changes in the molecular binding between ZnO and Ca, Fourier Transform Infrared spectroscopy (FTIR), Micro-Raman Spectroscopy and X-ray diffraction (XRD) were performed. The surface morphology and the chemical constituents distribution of the films were studied through Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and Atomic Force Microscopy (AFM), respectively. The optical and electrical properties were studied by UV–Vis spectroscopy, Spectral ellipsometry and electrical I–V measurements. The results show that the properties of prepared ZnO thin films were strongly influenced by the molarity concentration and Ca-dopant. The band shape obtained at FTIR is a band attributable to metal oxide bonds and can be attributed to the vibrational assignment of Zn–O bond. SEM-EDX and AFM investigations reveal an enlarged surface area due to the porous nature of the thin films and confirm the presence of Ca in the ZnO matrix. The XRD and Raman analyses indicate the achievement of the high crystalline quality and confirm the wurtzite phase of the synthesized thin films. The films transmittance spectra indicate values between 81 and 93% in the 350–800 nm wavelength region. We further performed I–V characteristics, resulting that Ca has a different impact of the electrical performances.

Effect of Indium Doping on Optical Parameter Properties of Sol–Gel-Derived ZnO Thin Films

Abstract Zinc oxide (ZnO) has gained great interest for two decades, and its structural, optical, and electrical properties have been investigated by scientists for technological applications. The optical properties of ZnO provide an opportunity for its application in solar cells, lasers, and light-emitting diodes. We prepared ZnO thin films with various In doping levels by using a spin coating technique, and characterised their morphological and detailed optical properties for optical applications. According to the morphological properties obtained by atomic force microscopy, the film surfaces are homogeneous and the In doping level affects the surface morphology of the films. The optical properties of the films were investigated using an ultraviolet–visible spectrometer, and some optical parameters such as band gap, refractive index, extinction coefficient, single oscillator parameters, real and imaginary functions of the dielectric coefficient, and optical conductivity were calculated and discussed in detail. The various In doping levels affected the optical properties, and the In-doped ZnO thin films can find applications in industry.

Bis(2-hydroxy-1-naphthaldehydato)zinc(II) as a precursor for the preparation of ZnO thin films through aerosol-assisted chemical vapour deposition

Bis(2-hydroxy-1-naphthaldehydato)zinc(II) complex was used as a precursor to deposit ZnO films on glass substrates at 350, 400, and 450 °C using aerosol assisted chemical vapour deposition (AACVD) technique. The optical properties of the films were investigated by UV–vis spectroscopy and photoluminescence (PL). The results show that temperature of decomposition has a huge effect on the material deposited. The optical characterization of ZnO thin films deposited on the glass substrate reveal the direct optical band gap in the range of 3.15 to 3.08 eV. The photoluminescence spectra were red shifted as the decomposition temperature was increased. The diffraction patterns of all ZnO thin films prepared at different temperatures show the face centred cubic structures with the lattice parameter of a = b = c = 4.289 A°. The structural properties of the ZnO thin films show an improvement in crystallinity of the materials when the temperature was increased.