Fabrication of high quality zinc-oxide layers through electrohydrodynamic atomization (original) (raw)
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Materials Science-Poland, 2019
An aqueous colloidal solution was prepared at 80 °C and pH = 9 from suitable chemical compounds to produce zinc oxide (ZnO) crystals and thin films. The ZnO crystals were grown in the colloidal solution under special conditions. Their micrographs showed ZnO rods with hexagonal structure. The number of the rods, increased over time. The ZnO thin films were produced on glass substrates in the same colloidal solution using the chemical bath deposition (CBD) method in different deposition times. The produced films were post-annealed for about one hour at 400 °C. Crystalline structure, phase transitions and nanostructure of the films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). ZnO wurtzite structure was dominant, and by increasing the deposition time, the films became more crystalline. Nanostructure of the films changed from rod to wire and transformed into pyramid-like structures. Also, morphology of the films chang...
Thin Solid Films, 2006
Indium doped zinc oxide [ZnO:In] thin films have been deposited at 430°C on soda-lime glass substrates by the chemical spray technique, starting from zinc acetate and indium acetate. Pulverization of the solution was done by ultrasonic excitation. The variations in the electrical, structural, optical, and morphological characteristics of ZnO:In thin films, as a function of both the water content in the starting solution and the substrate temperature, were studied. The electrical resistivity of ZnO:In thin films is not significantly affected with the increase in the water content, up to 200 mL/L; further increase in water content causes an increase in the resistivity of the films. All films show a polycrystalline character, fitting well with the hexagonal ZnO wurtzite-type structure. No preferential growth in samples deposited with the lowest water content was observed, whereas an increase in water content gave rise to a (002) growth. The surface morphology of the films
Thin ZnO films prepared by chemical solution deposition on glass and flexible conducting substrate
2005
Thin films of zinc oxide (ZnO) are deposited by a simple method of successive immersion of substrate in (NH 4) 2 ZnO 2 (0.1 M) chemical solution and in boiling water. Films of a thickness ≈ 500 nm could be deposited on stainless steel and glass by 40 immersions. The composition, structure, optical bandgap and the charge transport mechanism were determined and the results are presented. Films are stoichiometric and have the same hexagonal lattice parameters as for powder samples. Films are formed from grains with a mean size of a few 100 nm. Grains consist of crystallites of mean size 20-30 nm. For films deposited on stainless steel, the crystallites are highly oriented along their c-axis perpendicular to the substrate. Films have a high optical transparency (above 80%) in the visible region and bandgap energy in the range 3.38-3.42 eV. Films are intrinsically n-type and the charge transport across the films is controlled by a shallow trapping level in accordance with the Poole-Frenkel mechanism. The doubly-ionized trapping level has a concentration of 4 × 10 11 cm −3 and zero-field ionization energy of 110 meV. Adsorption of oxygen by annealing the films in air yields a singly-ionized trap.
The synthesis and characterization of sprayed ZnO thin films: As a function of solution molarity
Main Group Chemistry, 2015
In the present paper, the structural, electrical and optical properties of zinc oxide thin films were studied as a function of solution molarity. The ZnO thin films were deposited on glass substrates via the ultrasonic spray technique at 350 • C. Polycrystalline films with a hexagonal wurtzite structure with (100) and (002) preferential orientation corresponding to ZnO films were observed. The optimal values of the crystallite size of the ZnO films were observed with (002) plan in 0.4 and 0.5 mol/l of solution molarity. All films exhibit an average optical transparency about 85%, in the visible region. The shift of optical transmittance towards smaller wavelength can be showed by the decrease of band gap caused by the change of crystallite size in polycrystalline. The maximum electrical conductivity of ZnO films was found of 2.29 (.cm)-1 with 0.075 mol/l of solution molarity.
On the structural and electrical characteristics of zinc oxide thin films
Thin Solid Films, 2010
ZnO thin films with thickness d = 100 nm were deposited by radio frequency magnetron sputtering onto glass substrate from different targets. The structural analyses of the films indicate they are polycrystalline and have a wurtzite (hexagonal) structure. Crystallites are preferentially oriented with (002) plane parallel to the substrate surface and the samples have low values for surface roughness, between 1.7 nm and 2.7 nm. The mechanism of electrical conduction in the studied films is strongly influenced by this polycrystalline structure and we used Van der Pauw method to analyze these properties. Electrical studies indicate that the ZnO thin films are n-type. For the cooling process, thermal activation energy of electrical conduction of the samples can vary from 1.22 eV to 1.07 eV (for the ZnO layer obtained from for metallic Zn target) and from 0.90 eV to 0.63 eV (for the ZnO layer obtained from ZnO target), respectively. The influence of deposition arrangement and oxidation conditions on the structural and electrical properties of the ZnO films was investigated in detail.
1998
Transparent conducting zinc oxide films were grown by metalorganic chemical vapor deposition using diethylzinc/H2O and dimethylzinc/H2O reactant systems. The dimethylzinc/H2 O reactant system was introduced for the first time in this study to grow ZnO films. A very high growth rate of 10 μm/h was obtained. The B2H6 was also employed is an n-type dopant to lower the sheet resistivity of the films. By optimizing the B2H6 flow rate, the films with a sheet resistivity as low as 4 Ω/sq was achieved. The films showed a high transmittance of around 90% in a wavelength range from 400 nm to 1000 nm, suggesting their suitability to be used as transparent conducting materials