International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Special Issue: 09 | Sep -2017
p-ISSN: 2395-0072
www.irjet.net
One Day International Seminar on Materials Science & Technology (ISMST 2017) 4th August 2017 Organized by
Department of Physics, Mother Teresa Women’s University, Kodaikanal, Tamilnadu, India
Synthesis and characterization of ZnS nanostructured thin films using chemical spray pyrolysis Dhanasekaran D1, Bincy John2, Leo Rajesh A3 1,2,3 Department
of Physics, St. Joseph’s College (Autonomous), Tiruchirappalli, Tamilnadu *Corresponding author’s Email ID: aleorajesh@gmail.com ---------------------------------------------------------------------***--------------------------------------------------------------------
Abstract - Zinc Sulfide (ZnS) nanostructured thin films were
prepared by spray pyrolysis technique using aqueous of Zinc nitrate and Thiourea at a molar ratio 1:1. The depositions were carried out on substrate temperature at 400 0C. The structural, optical, morphological and elemental composition of the deposited films were characterized by X- ray diffraction (XRD), Photoluminescence (PL), UV-visible spectroscopy, Field Emission Scanning Electron Microscope (FESEM) with Energy Dispersive Analysis (EDAX). XRD result showed that the obtained sample had cubic phase with the average crystallite size of 3.84 nm. The surface morphology of the deposited film showed that the particles were in sphere like shape. The optical properties showed that the obtained ZnS nanostructured thin film were having the band gap energy of 3.5 eV and the PL gave the emission in the wavelength range of 350 nm. These results indicate that ZnS material is suitable for optoelectronic device application. Key Words: ZnS, Spray pyrolysis, XRD, FESEM, Optoelectronic application
1. INTRODUCTION Zinc sulfide is a semiconducting material with II-VI group compound, having the wide direct band gap energy of 3.65 eV [1]. Also ZnS semiconductor has n-type conductivity and is a promising material for optoelectronic devices, such as solar cells, antireflective coating, electroluminescent displays, optical sensors devices [2-5], UV-light emitting diodes, blue light emitting diode and emission flat screens [6,7]. Various techniques including both physical and chemical methods have been employed to prepare ZnS thin films. The physical methods including thermal evaporation [8], RF sputtering [9], pulsed laser deposition [10], atomic layer deposition [11] and these methods require expensive high vacuum systems for the deposition. The non vacuum based chemical methods are chemical bath deposition [12], spray pyrolysis [13][18], chemical precipitation [14], sol-gel and solvothermal method [15-16]. Among these, spray pyrolysis is the most popular deposition method because simple, low © 2017, IRJET
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cost, minimal waste product, ability to coat large surface area and easy to include in an industrial production line [17]. The present study report the deposition of ZnS nanostructured thin films have been carried out using chemical spray pyrolysis techniques. The influence of substrate temperature at 400 ˚C on the surface of the deposited film is studied using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) with energy dispersive spectrometer (EDS), UV- Visible and Photoluminescence (PL) spectroscopy.
2. EXPERIMENTAL DETAILS 2.1 Materials The chemical reagents were purchased from Merck Company and used without further purification for the preparation of ZnS thin films. Zinc nitrate heptahydrate (ZnNO3.7H2O) and thiourea (SC(NH2))2 were prepared Zinc nitrate, thiourea and deionized water were the materials and solvent respectively.
2.2 Experimental Procedure Thin films of ZnS were deposited on to the glass substrate using Spray pyrolysis technique. Glass substrates were cleaned by sonication for 15 min each in soap solution followed by dilute HCl and finally with double distilled water. After the cleaning process, the substrates were dried completely in air and placed on the plate to start the deposition process. The precursor solution was prepared using molar concentration 0.1M (0.89247g) of zinc nitrate (ZnNo3.7H2O) and 0.1M (0.2283g) of thiourea ((SC(NH2)2) in deionized water. The solution was kept for stirring 30 min to dissolve all the particles completely and to obtain a clear solution. The obtained clear solution was used for the deposition of nanostructured ZnS thin films at a temperature of 400˚C and continuous coating had been taken place. The spray pressure was 1.4 bars and the distance between the spray nozzles to the substrates was around 2025cm. ISO 9001:2008 Certified Journal
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