Effect of Al concentration on optical parameters of ZnO thin film derived by Sol-Gel dip coating technique (original) (raw)
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Influence of Al content on microstructure and optical transmittance of sol-gel dip-coated ZnO films
Synthesis and Sintering
Aluminum-doped zinc oxide thin film (Al:ZnO) was derived by the sol-gel dip-coating technique to analyze the doping effect on the film’s crystal structure and optical transparency. The surface structure of the thin film had the particles in the nano-spherical form. Al amount changed surface roughness with the variation of the grain size. The crystal structure of ZnO was wurtzite (in XRD analysis). The surface morphology of the film was also examined with SEM images. The effect of Al doping was investigated to evaluate the necessary amount of Al on the optical properties. The films show high optical transparency (~85%) at specific Al doping amounts (0.8-1.6%).
2012
Aluminum-doped zinc oxide thin films were deposited on glass substrates by the sol-gel technique. The effect of the Al concentration in the starting solution on the structural and optical properties of ZnO : Al thin films were studied. The molar ratio of the dopant (aluminum nitrate) in the solution [Al/Zn] was varied between 1% and 3%.The deposition of the layers was realized performed at room temperature by the dip-coating technique. The obtained films were inserted to a furnace and annealed at 500°C for 60 min. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and optical transmittance were used to characterize the elaborated samples. XRD results show that the films have hexagonal structure and grow preferentially along the crystallographic direction (002). The average crystallite size estimated by the Scherrer formula is about 5 nm. FT-IR spectrometry showed all types of molecular vibrations in the films and confirmed the formation of a ZnO semiconductor in the samples. The refractive index and thickness of layers were determined from the optical transmittance spectra. We observed that an increase in the Al content in the solution leads to an increase in the films thickness and a decrease in their refractive index.
Preparation and characterization of Al doped ZnO thin films by sol–gel process
Journal of Alloys and Compounds, 2012
Transparent conductive ZnO films doped with 0-5 mol% of Al 3+ (or AZO films) were deposited on the soda-lime glass substrates by sol-gel multilayer dip-coating. The effects of the processing conditions, especially annealing in vacuum, on the structure, optical and electrical properties of the AZO films were investigated by XRD, Raman spectroscopy, TEM and SEM, spectrophotometer, four-point prober and Halleffect measurements. Al 3+-doping led to destruction and reorganization of ZnO structure, but AZO films still had a hexagonal wurtzite structure with a preferential orientation along (0 0 2) crystal plane. After annealed in vacuum, the AZO films had better optical transmittance (>90%) and conductivity (smaller by two orders of magnitude), since annealing in vacuum promoted the growth of grains and release of residual stress, and also decreased the defects and disorder in the films. But extending the vacuum annealing time, the grains grew along other orientations except (0 0 2) crystal plane, so that the film's square resistance became bigger. Carrier concentration ($2.3 Â 10 19 /cm 3) of annealed AZO films increased with increasing Al 3+ amount, but Hall mobility in the 1% Al-ZnO film was the biggest, $19.1 cm 2 /Vs.
INFLUENCE OF ALUMINUM CONCENTRATION ON THE ELECTRICAL AND OPTICAL PROPERTIES OF ZnO THIN FILMS
Journal of the Turkish Chemical Society, Section A: Chemistry, 2016
Al:ZnO (AZO) thin films having with different Al concentrations were deposited on glass substrates by a sol-gel technique. The effects of Al doping on the structural, optical, and electrical properties of Al:ZnO were investigated using with XRD, optical transmittance, and sheet resistance measurements. The concentration of zinc acetate was 0.1 M. Al content in the starting solution was varied from 0 to 20% as the molarity range. Optical transmittance spectra of the films in the form of Film/Glass were used to determine the film thickness and optical band gaps. The optical transmissions of Al:ZnO thin films were higher than 80% in the visible and near infrared region. The optical band gaps of Al:ZnO films decrease with increase of Al content. In order to obtain the average sheet resistance of the films the current and voltage through the probes have been measured for five different position by four-point probe method. The results showed that the sheet resistances of Al:ZnO thin films increased with the Al concentration. Considering the film thickness and geometric factor, the electrical resistivity values were computed. It was observed that the sheet resistance of AZO films up to 10% molarity of Al in the starting solution increased.
Characterization of ZnO and ZnO:Al thin films deposited by the sol-gel dip-coating technique
2008
Nanocrystalline zinc oxide films have been obtained by the sol-gel process. The films were deposited from precursor solutions by dip-coating on quartz substrates, and subsequently transformed into nanocrystalline pure or aluminium-doped ZnO films after a thermal treatment. The film microstructure and composition characterization was studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The optical properties were studied by transmittance spectroscopy. The water adsorption energy was measured by temperature programmed desorption (TPD) in the range 90-700 K. The optical transmittance in the UV region gives bandgap energy values of 3.27 eV for undoped samples, and higher than 3.30 eV for the Al-doped ones. The increase in bandgap energy in Al-doped samples may be explained by band-filling effects. The band edge absorption coefficient increases monotonically for the Al-doped samples but has a shoulder for the undoped ones, which may be assigned to room-temperature excitonic absorption.
Effects of Al dopant on structural and optical properties of ZnO thin films prepared by sol-gel
Przegląd Elektrotechniczny, 2013
Transparent and conductive Al doped ZnO thin films were synthesized at room temperature by sol gel technique both pure ZnO and Al- doped(1,3,and5%) thin films were deposited on a glass substrate. The sols were prepared using zinc acetate dehydrate and aluminum chloride provides Al ions, played an important role in improvement of the c - axis, the structural characteristics have been studied by X-ray diffraction, and UV-Vis-NIR spectroscopy. The films are transparent from the near ultraviolet to the near infrared, SEM image also showed that the average grain size is decreased with increasing of Al concentration, band gap values of prepared thin films varied in the range of (3.18 - 3.42 eV). Streszczenie. Przejrzyste i przewodzące cienkie warstwy Al domieszkowane ZnO zostaly zsyntetyzowane w temperaturze pokojowej techniką zol- zel. Na podlozu szklanym naniesiono cienkie warstwy Al niedomieszkowanego oraz domieszkowanego ZnO w stosunku 1, 3, i 5%. Zole zostaly przygotowane wykorzystuj...
Al-doped ZnO thin films by sol?gel method
Surface and Coatings Technology, 2004
Transparent and conductive high preferential c-axis oriented ZnO thin films doped with Al have been prepared by sol-gel method using zinc acetate and aluminium chloride as cations source, 2-methoxiethanol as solvent and monoethanolamine as sol stabilizer. Film deposition was performed by dip-coating technique at a withdrawal rate of 1.5 cm min on Corning 1737 glass y1 substrate. The effect of dopant concentration, heating treatment and annealing in reducing atmosphere on the microstructure as well as on the electrical and optical properties of the thin films is discussed. The optical transmittance spectra of the films showed a very good transmittance, between 85 and 95%, within the visible wavelength region. The minimum resistivity of 1.3=10 V y3 cm was obtained for the film doped with 2 wt.% Al, preheated at 400 8C and post-heated at 600 8C, after annealing under a reduced atmosphere of forming gas.
Electrical and optical properties of dip coated Al-doped ZnO thin films
Mongolian Journal of Chemistry
Undoped and Aluminum doped Zinc Oxide thin films were synthesized by dip coating technique. The electrical properties of the films were studied due to the Aluminum doping, starting solution aging and sample aging. The sheet resistance of ZnO:Al films was minimum at 2.5 at % whereas carrier concentration is maximum. Both undoped and aluminum doped Zinc Oxide thin films were found to be highly transparent lying in between 65 - 79 % in the wavelength range 367 nm to 1038 nm. The band gap of deposited films changed slightly from 3.22 eV to 3.27 eV.
7TH NATIONAL CONFERENCE ON HIERARCHICALLY STRUCTURED MATERIALS (NCHSM-2019)
Zinc Oxide (ZnO) have been widely studied due to their wide band gap of ~3.37eV and thus is a potential candidate for the applications in transparent conducting devices. The influence of aluminum dopant (0-3.0 mol%) on ZnO thin films concerning structural and optical properties are investigated. Al doped ZnO (AZO) thin films are deposited on glass substrate by sol-gel spin coating technique with different parameters. Zinc acetate dihydrate, isopropanol and monoethanolamine were used as the starting material, solvent and stabilizer, respectively. The structural properties were studied through X-Ray diffraction and was found that all films exhibit c-axis preferential orientation with a hexagonal wurtzite crystal structure. The optical transmittance found using UV-Vis spectra was ~75% for all films in the visible region.
Sol-gel Aluminum-doped ZnO thin films: synthesis and characterization
Sol-gel Aluminum-doped ZnO thin films: synthesis and characterization, 2017
Zinc oxide is one of the most important n-type semiconductor intensively utilized in solar cells, transparent conducting electrodes and opto-electronic devices. Zinc oxide (ZnO) and Aluminum-doped Zinc oxide (AZO) thin films have been deposited by the spin-coating method. Their structural, optical and electrical proprieties were investigated. The X-Ray diffraction shows the polycrystalline hexagonal wurtzite structure exhibiting degradation in crystallinity of elaborated films with increasing Al doping concentration. This effect is reflected on optical and electrical proprieties of films. Indeed, the samples present a low optical transmittance level and the band gap values between 3.17 eV and 3.20 eV. Concerning the electrical properties, a decrease in the concentration of free charges carriers is observed as well as a decrease in resistivity.