Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Gas Sensor

Effect of Substrate Temperature on Nanostructure Titanium Dioxide Thin Films Prepared By PLD

Khaled Z.Yahya; Adawiya J. Haider; Heba Salam Tarek; Raad M. S. Al-Haddad

Engineering and Technology Journal, 2014, Volume 32, Issue 3, Pages 434-443

In this work, a double frequency Q-switching Nd:YAG laser beam (λ=532nm, laser fluence 1.2 J/cm2 ,repetition rate 10 Hz and the pulse duration 7ns) has been used, to deposit TiO2 thin films pure on glass and Si (111) substrates .The structure properties of pure TiO2 were investigated by means of x-ray diffraction. As a result, it has been found that film structure and properties strongly depended on substrate temperature. X-ray diffraction (XRD) showed that at substrate temperatures higher than 300 °C the structure of the deposited thin films changed from amorphous to crystalline corresponding to the tetragonal TiO2 anatase phase.The surface morphology of the deposits materials have been studied using scanning electron (SEM) and atomic force microscopes (AFM). The grain size of the nanoparticles observed at the surface depended on the substrate temperature, where 500°C was the best temperature and partial pressure of oxygen 5×10-1 mbar was the best pressure during the growth process. RMS roughness increased with increasing substrate temperature (Ts) which are (11.2nm) for thin films deposited at (500)ºC.UV-VIS transmittance measurements have shown that our films are highly transparent in the visible wavelength region, with an average transmittance of ~90% which makes them suitable for sensor applications . The optical band gap of the films has been found to be 3.2 eV for indirect transition and 3.6 eV for direct transition at 400˚C.The sensitivity toward CO gas has been measured under 50 ppm.

Study on the Effect of Annealing on Structural and SensingProperties of CdO Thin Films for (CO2 ,H2S) Gases

Hayder Mohammed Ajeel; Shatha Shammon Batros; Ashwaq Abdul Hussin Jabor; Karamh Abd Ali

Engineering and Technology Journal, 2012, Volume 30, Issue 19, Pages 3410-3420

Cadmium oxide (CdO) thin films have been deposited by Successive Ionic
Layer Adsorption and Reaction (SILAR) method by using cadmium acetate at
concentration 0.03 M and based solution from ammonium hydroxide on glass
substrate. The structural and sensing properties of the as -deposited and annealed
films are studied in details. The XRD and AFM analysis for its structural
characteristic has been preformed .The average grain size of deposited film are
increased after annealing . The sensing properties also are calculated and it is
found that the sensitivity are increasing after annealing, and for CO2 gas are
better than the sensitivity for H2S gas . The I-V properties are calculated for the
films before and after annealing for the two gases.