Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : thin films


Investigation of pyrolysis method for preparing CdO:In2O3 thin films gas sensor for NO2 gas

Shatha Shammon Batros

Engineering and Technology Journal, 2015, Volume 33, Issue 6, Pages 1134-1144

A novel CdO:In2O3nano composite has been synthesized by a pyrolysis method. The prepared nano composites have been carefully characterized using X ray diffraction and atomic force microscopy. The obtained results showed that the synthesized nano compositeCdo:In2O3 at optimum conditions has excellent grains. It was found that synthesized CdO:In2O¬3nano composite can be used as NO2 gas sensing to exhibit the highest sensitivity for NO2 at 200°C. The constructed sensor showed a very low detection limit of 5 ppm .

Study of Structural , Optical and Electrical Properties for Cr -Doped Tio2 Sensor for NH3 Gas

SelmaM.H.Al-Jawad; Zahraa Yassar Abbas

Engineering and Technology Journal, 2014, Volume 32, Issue 6, Pages 1137-1145

Titanium doxide (TiO2) thin films were deposited on quartz substrates by spray pyrolysis method using titanium tetrachloride as precursor solution. Thin films were deposited at temperature substrate 350 ◦C and annealed at 550 ◦C in air for 120 min. Polycrystalline thin films with anatas crystal structure, as evidenced from X-ray diffraction pattern. Optical study shows the optical band gap has been increased with increasing of dopant. Electrical properties have been studied by means of electrical resistivity and Hall measurement. The sensitivity of TiO2: 5% Cr to NH3 gas with concentration 5ppm at room temperature has been modified to (93) % as compared with a pure TiO2.

Comprehensive Electrochemical Evaluation of Protective Coatings Properties by Sol-Gel Route for Stainless Steel Corrosion

Atia; Mohammed Hussein J. Al

Engineering and Technology Journal, 2013, Volume 31, Issue 4, Pages 71-86

Sol gel nano ceramic coatings have been applied on stainless steel to develop their biological characteristics and increase resistance to corrosion and wear. In this work nine electrochemical parameters were calculated, adopted to set a comprehensive evaluation map for protective properties of the coatings obtained based on occurrence degree of cracks, porosity, general and localized corrosion by using d.c. Potentiostate utilized for measuring the polarization curve in 3.5% NaCl solution at 250C for a single alumina layer deposited on stainless steel specimens by the dipping technique from four solutions containing different alumina concentration 0.25, 0.26, 0.61 and 0.93 mole/liter prepared by dissolving aluminum isopropoxide in water, the coats were then heat treated to 6000C. The results showed the possibility of obtaining clear protective properties that facilitate the comparison between the types of thin coatings deposited on the surfaces of the stainless steel by sol gel method.

Laser Energy Effects on Optical Properties of Titanium Di- Oxide Prepared by Reactive Pulsed Laser Deposition

Mukkaram. A Fakhry; Farah A. Hattab; Esraa K. Hamed

Engineering and Technology Journal, 2012, Volume 30, Issue 17, Pages 3104-3111

In this Work, Laser energy effects on optical and morphological properties of
TiO2 thin film has been carried out using Reactive Pulsed Laser as a Deposition
technique (RPLD). Q-switched Nd-YAG laser with (ë=1.06ìm, t =7nsec) and
different energies have been used to ablate pure Titanium target and deposited thin
films on glass substrates with constant substrate temperature of (343K). The optical
properties of the films prepared include Optical transmit ion and absorption
measurement, surface uniformity measurement and FTIR structure of these films.
The results films show that high transparency reached to about (85-98) % can be
achieved with TiO2 film which itself decreases sharply with the increasing of Laser
energy while the optical band gap is (3.7-3.9) eV at optimum Laser energy in all
results (800mJ), the FTIRstructure result at 800 mJ is the optimum and peaks
absorption of TiO2 are (408.91, 439.77, 524.64) cm-1.

Transparent Oxide MgO Thin Films Prepanred By Reactive Pused Laser Deposition

Evan T. Salem; Farhan A.Mohamed

Engineering and Technology Journal, 2010, Volume 28, Issue 4, Pages 723-729

Transparent dielectric thin films of MgO have been deposited on glass
substrates at different oxygen pressure between (50-300) mbar using a pulsed laser
deposition technique to ablation of Mg target in the presence of oxygen as reactive
atmosphere. Structural, and optical, properties of these films have been
investigated. The films crystallize in a cubic structure and X-ray diffraction
measurements have shown that the polycrystalline MgO films prepared at oxygen
pressure (200) mbar and substrate temperature (150°C) with (111) and (002)
orientations. The films deposited at oxygen pressure between (150-300) mbar and
substrate temperature (150°C) exhibited highest optical transmittivity (>80%) and
the direct band gap energy was found to be 5.01 eV at oxygen pressure (200) mbar.
The measured of the resistivity of the film prepared at oxygen pressure (200) mbar
and substrate temperature (150°C) was 1.45x107Ω cm.

Increasing the Conductivity of Cadmium Telluride Films

Muslm Fadhel Al-Zubadi; Waseem Najeeb Ibrahim

Engineering and Technology Journal, 2009, Volume 27, Issue 14, Pages 2682-2691

The structural , optical and electrical properties of vacuum-evaporated CdTe thin films were investigated as a function of post-deposition annealing without and with CdCl2 treatment at 300˚C for 15min . X-Ray diffraction studies of the asdeposited films revealed polycrystalline in nature with cubic structure . The intensity of the (111) peak increased with the CdCl2 annealing treatment , and there is an increasing in the grain sizes after the CdCl2 annealing treatment with voids around the grain boundaries from the surface morphologies after the CdCl2 annealing treatment . The optical band gap values , Eg , were 1.56, 1.54 and 1.38 eV for film deposited at room temperature and after annealing without and with CdCl2 treatment at 300˚C for 15min respectively . Furthermore , the activation energy decreases after heat treatment without and with CdCl2 for CdTe thin films.

Optical Properties of ZnTe Thin Films Prepared By Chemical Spray Pyrolysis

Mohammed S.Mohammed

Engineering and Technology Journal, 2008, Volume 26, Issue 7, Pages 866-871

Thin films of ZnTe have been prepared by the method of chemical spray pyrolysis
.The absorption and transmissions spectra are recorded in the range 400-900nm.The
spectral dependences of absorption coefficient were calculated from transmission
spectra. The allowed direct and optical band gap energy has been evaluated from
(αhν)2 vs. (hν) plots. The optical constants such as extinction coefficient(k)and
refractive index (n) have been evaluated.

Optical Constants of Zinc Telluride Thin Films in the Visible and Near-Infrared Regions

Khalid Z. Yahiya; Evan T. Salem; Muhammad S. Muhammad

Engineering and Technology Journal, 2008, Volume 26, Issue 5, Pages 512-519

In this study, thin films of ZnTe were deposited on glass substrates using
vacuum evaporation technique. The optical measurements on the deposited films
were performed to determine the transmission spectrum and the absorption spectra
as a function of incident wavelength. As well, optical parameters, such as
extinction coefficient, value and type of energy gap, type of the dominant
absorption processes, real and complex refractive index as functions of incident
photon energy, were determined. This study may present better understanding for
the optical properties of ZnTe thin films and their devices in order to enhance their
characteristics and improve their efficiencies.