Enhanced Electrical Properties of Alkali-Doped ZnO Thin Films with Chemical Process (original) (raw)
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Optik, 2018
In this work, we have successfully prepared the highly conducting and transparent In doped ZnO thin films on glass substrate using sol-gel spin-coating technique. Indium was incorporated with different concentrations of 1, 2, and 4 at. %. The effect of Indium doping on the structural, optical and electrical properties of the produced films have been investigated. X-ray diffraction analysis showed that all the films were polycrystalline with a hexagonal würtzite structure.The growth along (002) orientation was only preferred for 2 at.% doping concentration. The transparency of In doped ZnO thin films varied from 70 to 92 % in visible range. Zinc oxide thin film doped with 4 at.% concentration revealed the largest grain size, the lowest optical gap, the highest intrinsic defects amount, and the lowest resistivity which was found to be 6.10×10-4 Ω.cm. These In doped ZnO thin films can have big interest in solar cell industry.
2018
In the present work, Ga-doped ZnO (GZO) thin films and ZnO nanorods (ZNRs) were fabricated for possible use as a transparent conducting oxide (TCO) film and a semiconductor oxide (SC) material, respectively, for photoelectrode component of the dye-sensitized solar cells (DSSCs). The GZO nanoparticles (NPs) were synthesized using the reflux-precipitation method, while ZNRs were grown on glass substrates seeded with an optimized GZO layer by the chemical bath deposition (CBD) method. The material properties of the samples were studied using various techniques. The X-ray diffraction patterns for all the GZO NPs and ZNRs exhibited a highly crystalline and hexagonal wurtzite structure of ZnO with no impurity phases. The values of the crystallite sizes range from 11 - 28 and 21 - 31 nm for the NPs and ZNRs samples, respectively. Peak shifts to lower diffraction angles from 47.45 - 47.35° with the increase in Ga/Zn solution pH was observed. A similar trend was observed also for other growt...
Journal of Theoretical and Applied Physics
Al-doped ZnO (AZO) thin films are deposited on glass substrate by sol-gel spin coating using zinc acetate dihydrate as a precursor with different molar concentrations varying from 0.35 to 0.75 mol/L. To investigate the structural, electrical, optical and morphological properties of AZO films, XRD, four-point probes, HE measurement, UV-Vis spectrometry and SEM with EDX are used. Thickness of the thin film is measured by a surface profilometer. The structural characteristics show a hexagonal wurtzite structure with a (002)-preferred orientation. Optical study reveals that transmittance is very high (up to 90%) within the visible region and optical band gap, E g varies from 3.25 to 3.29 eV with Zn concentration. The carrier concentration increases and resistivity decreases with the increase in Zn concentration. Thin films fabricated with 0.75 mol/L of Zn concentration exhibit the best electrical property. SEM study shows non-uniform surface of the films where EDX confirms the formation of AZO. The results revealed by this study prompt a high interest to use AZO as transparent conductive oxide for advanced applications such as displays, solar cells and optoelectronic devices.
Novel aluminum and indium doped zinc oxide bilayer transparent conducting oxide thin films have been developed by simple sol gel spin coating and annealed at 500 C for an hour under nitrogen ambient towards solar cell applications. The structural, electrical and optical properties of both the as deposited and annealed bilayer thin films are characterized. X-ray diffraction studies showed a hexagonal wurtzite-type structure of ZnO with (002) orientation, which was enhanced with annealing. In atomic force microscopy studies minimum surface roughness is attained for the Al-doped ZnO/In-doped ZnO bilayer TCO films. The best Al-doped ZnO/In-doped ZnO films had sheet resistance of 0.057 M ohm/square and the films had an average transmittance in the visible region over 90%. Further results are discussed with single and bilayer structure.
Materials Letters, 2018
Novel aluminum and indium doped zinc oxide bilayer transparent conducting oxide thin films have been developed by simple sol gel spin coating and annealed at 500 C for an hour under nitrogen ambient towards solar cell applications. The structural, electrical and optical properties of both the as deposited and annealed bilayer thin films are characterized. X-ray diffraction studies showed a hexagonal wurtzite-type structure of ZnO with (002) orientation, which was enhanced with annealing. In atomic force microscopy studies minimum surface roughness is attained for the Al-doped ZnO/In-doped ZnO bilayer TCO films. The best Al-doped ZnO/Indoped ZnO films had sheet resistance of 0.057 M ohm/square and the films had an average transmittance in the visible region over 90%. Further results are discussed with single and bilayer structure.
Optical and Structural Properties of ZnO Thin Films for Solar Cell Applications
Advanced Science Letters, 2013
In the present study, ZnO thin films are prepared successfully by simple and flexible spray pyrolysis technique on fluorine doped tin oxide glass substrate. The thermal spray deposition process is optimized by varying all the major parameters simultaneously: (1) precursor concentration; (2) substrate temperature; (3) carrier gas pressure; and (4) solution flow rate. Optical, structural and morphological properties are appropriately studied in detail. Most influencing parameters were observed to be the precursor concentration and substrate temperature, affecting film thickness, roughness, the band gap, and efficiency. It is confirmed that prepared films are uniform and crystalline in nature with a preferred orientation in (002) plane. The optical band gap is favourably in the range of 3.0-3.2 eV. At optimum conditions, the appropriate band gap (3.05 eV), thickness (89 nm) and roughness (2.38 nm) is achieved. The prepared films are consequently applied for perovskite solar cell preparation. Additionally, CuI (low-cost hole transport material) and carbon (counter electrode) are utilized. The efficiency of the device at optimum conditions is obtained to be maximum (3.21%). Maximum open circuit voltage (0.52 V), the maximum short circuit current (10.11 mA cm −2) and maximum fill factor (61%) is also achieved by the optimum device.
Thin Solid Films, 2012
Available online xxxx Sol-gel synthesis of intrinsic (i-ZnO) and aluminum-doped zinc oxide (Al:ZnO) thin films was carried out via spin coating process using 0.2 M Zn 2+ precursor salt, monoethanolamine to Zn 2+ ratio of 0.75, and 1 and 2 at.% aluminum as a dopant. After annealing at 500°C for 1 h, the structural, compositional, electrical, and optical properties of the films were investigated. Scanning electron microscope studies revealed smooth, dense film microstructure with granular cross-sectional morphology. The average grain size was in the range of 25 to 53 nm, depending on film composition, and indicated reduction in size with more Al incorporation. The processing conditions favored (002) preferential growth in all the films, with degree of preferred growth as high as 0.45, as determined from X-ray diffraction analysis. Al:ZnO film with 1 at.% Al was found to exhibit minimum resistivity value of 4.06 × 10 −3 Ω cm and carrier concentration as high as 5.52 × 10 19 cm −3 . From optical transmittance spectra, the absorption edge of the films was determined to be at~370 nm with ≥ 80% transmittance in visible and near-infrared regions of the spectrum. The calculated values of band gap indicated continuous increase from 3.35 to 3.41 eV upon Al doping of the films.
djelloul, 2018
Zinc oxide (ZnO) is an n-type semiconductor with a large optical gap (3.4 eV) belonging to the transparent conductive oxides family (TCO). Strongly present as optical window in the chalcopyrite based structures CIGS and CIS. The structural, morphological, optical and electrical properties of ZnO thin films deposited onto glass substrates by ultrasonic spray pyrolysis (USP) technique have been investigated. For comparison and a better understanding of physical properties of undoped and (Al, In) doped ZnO thin films, a number of techniques, including XRD, SEM, optical absorption method (UV) and four-point probe technique were used to characterize the obtained ZnO thin films. Structural analysis shows that all the films were found to be polycrystalline with a wurtzite structure and show a (1 0 1) preferential growth. Besides, we noted that the preferred orientation does not depend on the nature of dopant. The band gaps (Eg) varied from 3.35 to 3.37 eV by Al and In dopants.
Journal of Nano- and Electronic Physics, 2021
This work reports on the development and characterization of Zinc Oxide (ZnO) nanocrystalline thin films deposited on glass substrates by spray pyrolysis method. The effect of 1 % Mg-doping and 6 % F/ x % Mg co-doping (x 1, 2 and 3) on the structural, morphological, optical and electrical properties of the films obtained is studied. The structural characterization shows that all the deposited layers are polycrystalline with a hexagonal wurtzite-type structure due to the existence of a more intense peak relative to the (002) peak, located around an angle of 34.13° with no other phase detected. The measured contact angles are more than 90° for pure, doped and 6 % F/1 % Mg co-doped films prepared, which confirms the hydrophobic character, while other co-doped films (6 % F:2 % Mg and 6 % F:3 % Mg) show the hydrophilic character at values of the contact angle 90°. A higher transmittance value of 86.47 %, a wide band gap of 3.53 eV and lower disorder (330.03 meV) are observed for the 6 % F:1 % Mg co-doped film. Co-doping with 1 % Mg considerably improves the electrical conductivity ( 0.030 (Ω.cm)-1). The results suggest that the co-doped ZnO film (6 % F, 1 % Mg) can be used as a window film in thin film solar cells.
Journal of Applied Physics, 2017
Transparent conducting oxides such as ZnO doped with Al or Mg are commonly used in solar cells, light emitting diodes, photodetectors, and ultraviolet laser diodes. In our work, we focus on a comparative study of the structural, optical, and electrical properties of ZnO films highly doped with Al (AZO) and Mg (MZO). These films are deposited on glass substrates by the sol-gel spin coating method. The doping concentrations for Al and Mg are fixed to 5%–30%. The XRD spectra indicate that all the samples are polycrystalline with hexagonal wurtzite structures, exhibiting a preferred orientation along the (002) plane. Low degradation in crystallinity was observed for MZO even at a Mg concentration of 30%. The MgO phase started to appear compared to Al-doped layers where smaller grains are formed inducing a deterioration in the films just after doping but no new phase appeared. This result is in agreement with other experimental results [J. K. Rath, Sol. Energy Mater. Sol. Cells 76, 431–4...