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Synthesis and characterization of zinc oxide thin films for optoelectronic applications

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ABSTRACT

Micro-ring structured zinc oxide (ZnO) thin films were prepared on glass substrates by spray pyrolysis and their structural, morphological, optical and electrical properties were investigated. X-ray Diffraction (XRD) analysis revealed the films’ hexagonal wurtzite phase with a preferred (002) grain orientation. The mean crystallite size calculated on the basis of the Debye-Scherrer model was 24 nm and a small dislocation density of 1.7×10−3  nm−2 was obtained, indicating the existence of few lattice defects and good crystallinity. Scanning Electron Microscopy (SEM) micrographs revealed the film’s granular nature composed of rod-shaped and spherical nanoparticles which agglomerated to form micro-ring like film clusters on the film surface. The average transmittance in the visible region, optical band gap and Urbach energy were approximately 75–80%, 3.28 eV and 57 meV, respectively. The refractive index and extinction coefficient were determined using Swanepoel’s envelope method. Raman spectroscopy revealed the presence of small amounts of residual tensile stress and low density of defects in the ZnO thin films. This was consistent with XRD analysis. A low sheet resistivity (6.03×101  Ωcm) and high figure of merit (4.35×10−6  Ω−1) were obtained for our films indicating their suitability in optoelectronic applications.

No MeSH data available.


Variation of  versus  for the micro-ring structured ZnO thin film.
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fig0020: Variation of versus for the micro-ring structured ZnO thin film.

Mentions: where hν is the energy of the incident photon and B is an energy-independent constant. Eg was found to be 3.28 eV from the Tauc plot of versus , shown in Fig. 4, by extrapolating the linear portion of the absorption edge to . This was slightly less than 3.31 eV for bulk ZnO [41], due to grain boundaries and imperfections in the film [42]. However, this value was relatively greater than 3.22 eV for ZnO micro-rings [20], 3.15 eV [26] and 3.26 eV [24] for ZnO microrods and 3.18 eV [15] for ZnO microsausages.


Synthesis and characterization of zinc oxide thin films for optoelectronic applications
Variation of  versus  for the micro-ring structured ZnO thin film.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384418&req=5

fig0020: Variation of versus for the micro-ring structured ZnO thin film.
Mentions: where hν is the energy of the incident photon and B is an energy-independent constant. Eg was found to be 3.28 eV from the Tauc plot of versus , shown in Fig. 4, by extrapolating the linear portion of the absorption edge to . This was slightly less than 3.31 eV for bulk ZnO [41], due to grain boundaries and imperfections in the film [42]. However, this value was relatively greater than 3.22 eV for ZnO micro-rings [20], 3.15 eV [26] and 3.26 eV [24] for ZnO microrods and 3.18 eV [15] for ZnO microsausages.

View Article: PubMed Central - PubMed

ABSTRACT

Micro-ring structured zinc oxide (ZnO) thin films were prepared on glass substrates by spray pyrolysis and their structural, morphological, optical and electrical properties were investigated. X-ray Diffraction (XRD) analysis revealed the films’ hexagonal wurtzite phase with a preferred (002) grain orientation. The mean crystallite size calculated on the basis of the Debye-Scherrer model was 24 nm and a small dislocation density of 1.7×10−3  nm−2 was obtained, indicating the existence of few lattice defects and good crystallinity. Scanning Electron Microscopy (SEM) micrographs revealed the film’s granular nature composed of rod-shaped and spherical nanoparticles which agglomerated to form micro-ring like film clusters on the film surface. The average transmittance in the visible region, optical band gap and Urbach energy were approximately 75–80%, 3.28 eV and 57 meV, respectively. The refractive index and extinction coefficient were determined using Swanepoel’s envelope method. Raman spectroscopy revealed the presence of small amounts of residual tensile stress and low density of defects in the ZnO thin films. This was consistent with XRD analysis. A low sheet resistivity (6.03×101  Ωcm) and high figure of merit (4.35×10−6  Ω−1) were obtained for our films indicating their suitability in optoelectronic applications.

No MeSH data available.