Influence of precursor concentration on structural, morphological and electrical properties of spray deposited ZnO thin films

Electrical and Electronics Engineering Department , SASTRA University, Tanjor, Tamil Nadu, India
Crystal Research and Technology (Impact Factor: 0.94). 07/2011; 46(7):685. DOI: 10.1002/crat.201000672


Nanostructured ZnO thin films were coated on glass substrate by spray pyrolysis using Zinc acetate dihydrate as precursor. Effect of precursor concentration on structural, morphological, optical and electrical properties of the films was investigated. The crystal structure and orientation of the ZnO thin films prepared with four different precursor solution concentrations were studied and it was observed that, the prepared films are polycrystalline in nature with hexagonal wurzite structure. The peaks are indexed to (100), (002), (101), (102) and (110) planes. Grain size and texture coefficient (TC) were calculated and the grain size found to increase with an increase in precursor concentration. Presence of Zn and O elements was confirmed with EDAX spectra. Optical absorption measurements were carried out in the wavelength region of 380 to 800 nm and the band gap decreases as precursor concentration increases. The current-voltage characteristics were observed at room temperature and in dark. It was found that for the films deposited at four different precursor
concentrations, the conductivity improves as precursor concentration increases. As trimethylamine (TMA) is a good marker for food quality discrimination, sensing behavior of the films at an optimized operating temperature of 373 K, towards various concentrations of (TMA) was observed and reported.

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Available from: Durgajanani Sivalingam, Aug 06, 2014
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    • "This has confirmed the formation calcium carbonate due to the reaction between the exhausted CO 2 and calcium hydroxide. This mechanism may be possible at room temperature because of the enhanced specific surface area and hence the enhanced surface catalytic activity of the nano-sized grains [46] [47] [59]. Also, the enhanced electron density of states on the surface of the films converts the inactivated surface into a highly activated one. "
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    ABSTRACT: Randomly interconnected zinc oxide (ZnO) nanoplatelets were successfully deposited on glass sub-strates using simple chemical spray pyrolysis technique. X-ray diffraction (XRD) pattern confirmed that the nanoplatelets were highly polycrystalline in nature with hexagonal wurtzite structure. Field emis-sion scanning electron microscope (FE-SEM) image revealed the formation of randomly interconnected nanoplatelets with no visible defects on their surface. The thickness of the nanoplatelets was found to be in the range of 110–130 nm. The optical absorbance spectra showed no sharp absorption edge and the optical band gap was found to be 3.23 eV. Acetaldehyde sensing characteristics of ZnO nanoplatelets at room temperature were investigated. The selectivity of ZnO nanoplatelets towards acetaldehyde was found to be significant in comparison with the other gases like ethanol, methanol, ammonia, acetone, formaldehyde and toluene.
    Sensors and Actuators B Chemical 04/2014; 198:125-133. DOI:10.1016/j.snb.2014.02.101 · 4.10 Impact Factor
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    • "The structural features of the films were investigated using X-ray diffractometer (D8 Focus, Bruker, Germany) with monochromatic Cu K␣ radiation ( = 1.5418Å ) at 2Â range between 10 • and 60 • with a scan rate of 2 • /min. The average crystallite size D (h k l) was estimated using Debye Scherrer's formula [30], "
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    ABSTRACT: Nanostructured ZnO thin films were deposited on glass substrates at 503 K using spray pyrolysis tech-nique and the films were post annealed at 673 K in air atmosphere for 3 h. The structural, morphological and optical properties of as-deposited and annealed samples were investigated. The annealed films showed uniform spherical morphology in contrast with as-deposited films. XRD patterns of both the annealed and as-deposited films confirmed the polycrystalline nature of the films with hexagonal wurtzite structure. Room temperature ammonia sensing characteristics of annealed films were studied for various concentration levels of ammonia at dry air and humidity conditions. A highest room temper-ature response of 233 was achieved at 25 ppm of NH 3 with a response and recovery times of 20 and 25 s respectively. The response of the sensor to other gases such as methanol, ethanol, 2-propanol, benzyl alcohol and acetone indicated a high selectivity towards ammonia gas. The room temperature (303 K) operation, with high selectivity, repeatability and fast transition times of the sensor together with the low deposition cost suggests suitability for developing a low power cost-effective ammonia sensor.
    Sensors and Actuators B Chemical 04/2013; 183:459-466. DOI:10.1016/j.snb.2013.03.132 · 4.10 Impact Factor
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    • "This can also be theoretically explained using the second-order perturbation theory [25] [26] [29]. A huge variation in the band gap of Mn doped ZnO in comparison to the undoped ZnO [24] is because of the spatial confinement [30]. Viswanatha et al. [30] "
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    ABSTRACT: The influence of dopant precursor (manganese (II) acetate tetrahydrate) concentration on structural, morphological, optical and vapour sensing properties of zinc oxide (ZnO) was studied by fabricating manganese (Mn) doped ZnO thin films with various Mn2+ concentration, using spray pyrolysis technique. The as-deposited films were found to be polycrystalline in nature, with hexagonal wurtzite structure. A rope-like morphology was observed through secondary electron (SE) image. The I–V characteristics depict a decrease in electrical resistance with an increase in concentration levels of Mn2+. The optical band gap decreased from 3.45 eV to 1.9 eV, on increase in Mn2+ concentration from 0.002 M, 0.004 M and 0.006 M (Mn1, Mn2 and Mn3 samples) in 0.05 M of zinc acetate dihydrate. The vapour sensing behaviour of the films was observed for various concentrations of trimethylamine (TMA) and ethanol at an optimized operating temperature of 373 K. The sensor response for TMA was found to be more appreciable in comparison with the response towards ethanol. The response of TMA at 75 ppm was calculated to be 300, with a response and recovery time of 11 s and 20 s respectively.
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