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Bindu K.R.,Sree Sankara Vidyapeetom College | Sreenivasan P.V.,Union Christian College | Martinez A.I.,CINVESTAV | Anila E.I.,Optoelectronic and Nanomaterials Research Laboratory
Journal of Sol-Gel Science and Technology | Year: 2013

The structural, morphological, optical and electrical properties of α-axis oriented nanostructured ZnS thin film prepared by dip coating have been studied in this article. The X-ray diffraction studies of the film shows that the ZnS was crystallized with cubic structure of particle size 27 nm with a strong orientation along (200) plane which is advantageous for optoelectronic devices. The scanning electron microscopy and TEM micrograph reveals that the film consists of nano crystalline columnar particles. From the investigation of the absorption spectra of this ZnS film, the band-gap is found to be higher (4 eV) than bulk (3.7 eV) indicating a blue shift. It is found that the film is having a transparency of >90 % in the visible-near IR region from 400 to 800 nm. From the photoconductivity measurements, it is evident that the film is photosensitive in nature. From the electrical resistivity measurements the conductivity of the film was found to be 3.4 × 10-2 Ω-1 cm-1. Hot probe method indicates that the synthesized ZnS film is n-type. © 2013 Springer Science+Business Media New York. Source

Athma P.V.,Optoelectronic and Nanomaterials Research Laboratory | Athma P.V.,SNM College | Martinez A.I.,CINVESTAV | Johns N.,Indian Institute of Technology Bombay | And 3 more authors.
Superlattices and Microstructures | Year: 2015

Abstract Zinc oxide (ZnO) nanostructures find applications in optoelectronic devices, photo voltaic displays and sensors. In this work zinc oxide nanostructures in different forms like nanorods, tripods and tetrapods have been synthesized by thermal evaporation of zinc metal and subsequent deposition on a glass substrate by vapor transport in the presence of oxygen. It is a comparatively simpler and environment friendly technique for the preparation of thin films. The structure, morphology and optical properties of the synthesized nanostructured thin film were characterized in detail by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoluminescence (PL). The film exhibited bluish white emission with Commission International d'Eclairage (CIE) coordinates x = 0.22, y = 0.31. © 2015 Published by Elsevier Ltd. Source

Athma P.V.,Optoelectronic and Nanomaterials Research Laboratory | Athma P.V.,SNM College | Johns N.,Indian Institute of Technology Bombay | Anila E.I.,Optoelectronic and Nanomaterials Research Laboratory | Safeera T.A.,Optoelectronic and Nanomaterials Research Laboratory
Optical Materials | Year: 2014

This paper presents the synthesis of potassium (K) doped zinc oxide nano sheets at room temperature by wet chemical method. The structure and morphology of the crystals prepared for different molar concentrations of K were analysed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Lattice strain and grain size were calculated from the Williamson-Hall (WH) Plot and Debye-Scherrer's formula for different concentrations of potassium. Absorption studies reveal that absorption is minimum in the visible region and band gap energy is found to decrease with increase in K concentration. The photoluminescence (PL) spectra were used to study the luminescence behavior and the nature of defects in the samples and the overall emission is white for all the samples except the one prepared with 1.2 M potassium doping. © 2014 Elsevier B.V. All rights reserved. Source

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