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  • Author: Sharadrao A. Vanalakar x
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Abstract

This paper reports the chemical and mechanical stability of Molybdenum (Mo) thin films deposited by direct current magnetron sputtering technique onto soda lime glass substrates. Mo thin films were deposited at various Ar (working) gas pressures to get optimized structural, morphological, adhesive and electrical properties. Mo thin films were further characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction, Hall measurements and the cross hatch tape test. To study their chemical stability the prepared Mo thin films were further dipped in acetic acid and ammonia solution for 6 h. Mechanical stability of Mo thin films was tested by high speed ultrasonication for an hour. Both the chemical and mechanical stability studies showed that Mo thin films were highly stable since morphology, adhesion and electrical properties did not alter significantly. FE-SEM results showed that the grain size of the chemo-mechano stability tested Mo thin films remained significantly similar with an unimportant effect on the film thickness. Electrical properties showed that electrical resistivity and hall mobility for as-deposited Mo thin films were 2.7 · 105 Ω cm and 5.1 cm2/Vs, respectively and remained nearly stable regardless of chemical and mechanical treatment. All of the films passed the cross hatch tape test and showed an excellent adhesion with glass substrates. The wettability investigations showed that all the Mo thin films were hydrophilic in nature and having contact angles in the range of 35 to 40.

Abstract

Thin films of cadmium sulfide (CdS) with different film thicknesses were chemo-synthesized onto soda lime glass and fluorine doped tin oxide (FTO) coated glass substrates. The synthesized CdS films were characterized by using UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The XRD patterns revealed the formation of CdS with a cubic crystal structure. The variation in band gap energies was found to be in the range of 2.42–2.85 eV. An increase of 0.43 eV over the bulk band gap energy of CdS was found due to the quantum size effect in CdS thin films. The atomic force microscopy study depicted a novel egg-like morphology of CdS nanoparticles. Further, photoelectrochemical (PEC) performance of as grown CdS thin films was investigated using two electrode configurations in polysulfide electrolyte. The sample with film thickness 1389 Å showed the best PEC performance compared to other samples.

Abstract

The WO3 thin films have been synthesized on to the glass substrates by a simple and easy spin coating method at different deposition cycles and their sensor responses towards various concentrations of NO2 gas were investigated. The WO3 films were spin coated at a spinning rate of 2500–3000 rpm for 5, 10 and 15 deposition cycles, respectively. Then the films were annealed at 400 °C for 1 h in a furnace. The structural, morphological, optical and electrical properties of WO3 films were studied by different characterization techniques such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), FT-RAMAN Spectroscopy and electrical resistivity measurements by laboratory made two probe method respectively. It reveals a spherical grain – like morphology with a pure monoclinic phase of WO3. The FT-RAMAN spectra also confirm the pure monoclinic phase of WO3. The WO3-10 film sensor exhibits maximum gas sensitivity 21.93 and 102.4% to 5 and 100 ppm NO2 at 200 °C, respectively. The WO3-10 thin film sensors is highly sensitive and selective to NO2 over other gases.