The effect of heat treatment on the physical properties of sol–gel derived ZnO thin films

Abstract. Nanosized ZnO particles derived from chemical co-precipitation route were used for casting ZnO films by screen printing method followed by sintering at two different temperatures. The variation in structural, optical and electrical properties of these films with temperature have been investigated by XRD, SEM, FTIR, Raman, UV-VIS, EPR and four probe analytical techniques. XRD patterns of these films exhibit polycrystalline nature with hexagonal wurtzite structure and SEM images reveal the smooth, dense and without any cracks/damage porous surface morphology. Infrared transmission spectra shows peaks pertaining to Zn-O stretching modes and their multiphonon modes. While Raman spectra exhibited strong peaks of E 2 (high) phonon and overtone of surface phonon mode at 429 cm −1 and 1144 cm −1 respectively with weak components of LO and TO branches. The direct band gap energy of these films showed narrowing of band gap from 3.21 eV to 3.12 eV on increasing sintering temperature from 500 • C to 600 • C. DC conductivity measurements confirmed semiconducting behaviour and showed lowering of activation energy. EPR spectra showed single narrow line resonance signal of g-value ∼ 1.9469 due to oxygen vacancies which are produced during synthesis of ZnO nanoparticles by sol-gel process. These studies revealed that on increasing sintering temperature the crystallinity of the film improves with reduction in lattice deformations in these screen printed ZnO films.

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“…It has been found increase with increasing substrate temperature and the values are very close to the earlier reported result [26].…”

Section: Structural Analysissupporting

confidence: 91%

Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

Zargar

Arora

Hafiz

2015

Eur. Phys. J. Appl. Phys.

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“…The XRD spectra of the films indicate enhanced intensities for the peaks corresponding to (111) plane which also mention the preferential orientation along the specific plane by compar to the XRD pattern of cubic structure (JCPDS 01 The relative intensity of the peak plane increase with increasing annealing temperature. It is believed that the preferential orientation is due to the minimization of surface energy and internal stress [18].…”

Section: Resultsmentioning

confidence: 99%

“…The relative intensity of the peaks corresponding to the (111) crease with increasing annealing temperature. It is believed that the preferential orientation is due to the minimization of surface energy and internal stress [18]. ε) and dislocation density (δ) were calculated from the following formulas [14]:…”

Section: Resultsmentioning

confidence: 99%

Variation of Structural and Surface Properties of RF Sputtered Aluminum Oxide (Al2O3) Thin Films Due to the Influence of Annealing Temperature and Time

Qiang¹

2014

IJMSA

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Aluminum oxide (Al 2 O 3 ) thin films were deposited on Si (111) substrates by using RF magnetron sputtering of Al 2 O 3 target in Ar atmosphere. The synthesized films were annealed in the temperature range of 200 to 600°C in nitrogen (N 2 ) environment for 2 and 4 hours. Variations in these structural and surface properties of the films were investigated using X-ray diffraction (XRD) and atomic force microscope (AFM). XRD analysis reveals that the synthesized films are in polycrystalline form with preferential orientation along (111) plane. By increasing the annealing temperature, the crystallite size of films was found to increase, whereas the micro-strain and dislocation density were decreased. The decrease in micro-strain and dislocation density was ascribed to the reduction in the lattice strain. The surface roughness of the films was increased with the increase of the annealing temperature, which was attributed to the films' grains growth and also with the increase in RF sputtering power.

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“…The XRD peak can be widened by internal stress and defects, so the mean grain size estimated by this method is normally smaller than the actual value [24].…”

Section: Chemical Composition and Microstructurementioning

confidence: 97%

Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

Broitman

Bojorge

Elhordoy³

et al. 2012

Surface and Coatings Technology

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The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol–gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol–gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water

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The effect of heat treatment on the physical properties of sol–gel derived ZnO thin films

Cited by 301 publications

References 36 publications

Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

Variation of Structural and Surface Properties of RF Sputtered Aluminum Oxide (Al2O3) Thin Films Due to the Influence of Annealing Temperature and Time

Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

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