An Effect of Precursor Concentration on ZnO Thin Films Prepared by Dip Coating Method | Chapter 08 | New Insights on Chemical Research Vol. 1

Zinc Oxide (ZnO) thin films have been successfully coated onto glass substrates at various solutions concentration (0.1 M, 0.2 M and 0.3 M) by Low cost SILAR coating technique. The film thickness was estimated using weight gain method and it revealed that the film thickness increased with solution concentration values. The prepared film structural, morphological and optical properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-Vis-NIR spectrophotometer respectively. The structure of the films were found to be hexagonal structure with polycrystalline in nature with preferential orientation along (002) plane. X-ray line profile analysis was used to evaluate the micro structural parameters such as crystallite size, micro strain, dislocation density and stacking fault probability. The value of the crystalline size is increased by increasing the concentration of the solution. The average crystalline size was estimated at in the range of 26 nm to 29 nm. The morphological results showed that the concentration of a solution had a significant effect on the morphology of the ZnO thin films. The optical studies revealed that the band gap can be tailored between 3.65 eV to 3.85 eV by altering solution concentration. EDAX studies have shown the presence of zinc and oxygen content. Photoluminescence intensity varies with molar concentration due to the increase of oxygen vacancies. FTIR results conforms the presence of functional group present in the samples.

Author(s) Details

K. Radhi Devi
Department of Physics, Sethupathy Govt. Arts College, Ramanathapuram – 623 502, India.

G. Selvan
Department of Physics, Thanthai Hans Roever College, Perambalur – 621 220, India.

M. Karunakaran
Department of Physics, Alagappa Government Arts College, Karaikudi – 630 003, India.

K. Kasirajan
Department of Physics, Alagappa Government Arts College, Karaikudi – 630 003, India.

G. Rajesh Kanna
Department of Electronics, Government Arts College for Women, Ramanathapuram- 623 502, India.

S. Maheswari
Department of Physics, Alagappa Government Arts College, Karaikudi – 630 003, India and Department of Physics, Caussanel College of Arts and Science, Ramanathapuram – 623 523, India.

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Optical Properties of Te-Based Chalcogenide Alloys in the Mid- and Far Infrared Regions | Chapter 05 | New Advances in Materials Science and Engineering Vol. 1

Ternary telluride alloys of Ge–Se(Sb)–Te and Si–Ge(Ga)–Te systems are synthesized in glassy and crystalline states for use in the terahertz frequency range. The transmission spectra of the obtained alloys are measured and studied in a wide wavelength range from 0.75 to 300 μm. The possible mechanisms of their formation are discussed. A comparative analysis of the results shows that the Ge₁₄Sb₂₈Te₅₆ alloy of the GST system is most promising. Its phonon spectrum is in the range of 40– 280 cm^–1, limiting the long-wavelength transmission window of this alloy by 35 μm. Optimization of the Ge₁₄Sb₂₈Te₅₆ composition, the removal of impurities, and heat treatment will promote a further decrease in the absorbance in the far-infrared spectrum of this alloy.

Author(s) Details

V. A. Ryzhov
Ioffe Institute, St. Petersburg, 194021, Russia.

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Effect of Concentration on Morphological, Optical and Electrical Properties of Copper Doped Zinc Oxide Thin Films Deposited by Electrostatic Spray Pyrolysis (ESP) Technique | Chapter 03 | New Advances in Materials Science and Engineering Vol. 1

Pure zinc oxide (ZnO) and copper (Cu) doped ZnO thin films were synthesised from the precursor’s concentrations (zinc acetate and copper acetate) onto glass substrate via electrostatic spray pyrolysis (ESP) deposition technique at 350°C in air ambient with different Cu doping concentrations (0%, 5%, 10%, 15% and 20%). The thin films were analysed with regards to its morphological, optical, and electrical properties before and after annealing. The results indicate that the annealing of the thin films leads to improved surface morphology and better crystallinity quality. Nanofibers were observed around the nucleation centre in the pure ZnO thin films. The absorbance was recorded in the wavelength range of 230 nm to 1100 nm, and the optical transmission of the films was found to increase for increasing doping concentration of Cu up to 370 nm and then decreased for higher wavelengths. ZnO:Cu films displayed high optical transparency which is around 86% – 98% in the visible and infrared regions but minimum in the ultraviolet region. The band gap energy value of the pure ZnO films was found to be 3.20 eV, whereas the doped films revealed a continuous decreases for higher doping of Cu concentration, reaching a value of 2.66 eV. The refractive index of the films significantly changes with the deposition parameter and increases sharply from 1.4597 to 1.7865 and the highest electrical resistivity was found to be 8.83 μm, and the lowest optical conductivity of 0.113 MƱm-1 was observed in the films with 20% Cu doped film, which indicates that the deposited films are highly suitable for photovoltaic cells and other optoelectronic device applications.

Author(s) Details

D. O. Samson
Department of Physics, University of Abuja, P.M.B 117, Abuja, Nigeria and School of Physics, Universiti Sains Malaysia, 11800 USM, Gelugor, Penang, Malaysia.

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