Faculty Publications
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Item Properties of ZnO:Bi thin films prepared by spray pyrolysis technique(Elsevier Ltd, 2013) Sadananda Kumar, N.; Bangera, K.V.; Anandan, C.; Shivakumar, G.K.Undoped and Bi doped zinc oxide thin films were deposited on glass substrate at 450 °C using spray pyrolysis technique. The X-ray diffraction studies shows that Bi doped ZnO films are polycrystalline hexagonal structure with a preferred orientation along (101) direction. Crystallites size of the films decreases with increasing doping concentration. Scanning electron microscope image shows change in the surface morphology. The composition of Zn, O and Bi elements in the undoped and Bi doped ZnO films were investigated by X-ray photoelectron spectroscopy. Bi doped ZnO thin films show a transparency nearly 75% in the visible region. The optical band gap of ZnO thin films reduces from 3.25 eV to 3.12 eV with an increase in Bi concentration from 0 to 5at.% respectively. Electrical conductivity of ZnO thin films increased from 0.156 to 6.02S/cm with increasing Bi dopant concentration from 0% to 5% respectively. © 2013 Elsevier B.V. All rights reserved.Item Study of the doping of thermally evaporated zinc oxide thin films with indium and indium oxide(Springer Nature, 2013) Palimar, S.; Bangera, K.V.; Shivakumar, G.K.The present paper reports observations made on investigations carried out to study structural, optical and electrical properties of thermally evaporated ZnO thin films and their modulations on doping with metallic indium and indium oxide separately. ZnO thin film in the undoped state is found to have a very good conductivity of 90 ?–1 cm–1 with an excellent transmittance of up to 90 % in the visible region. After doping with metallic indium, the conductivity of the film is found to be 580 ?–1 cm–1, whereas the conductivity of indium oxide-doped films is increased up to 3.5 × 103 ?–1 cm–1. Further, the optical band gap of the ZnO thin film is widened from 3.26 to 3.3 eV when doped with indium oxide and with metallic indium it decreases to 3.2 eV. There is no considerable change in the transmittance of the films after doping. All undoped and doped films were amorphous in nature with smooth and flat surface without significant modifications due to doping. © 2012, The Author(s).Item Preparation of thermally deposited Cux(ZnS)1-x thin films for opto-electronic devices(Elsevier Ltd, 2019) Barman, B.; Bangera, K.V.; Shivakumar, G.K.Zinc sulfide thin films have been doped with copper atoms to investigate their efficiency as transparent conductor layers. Cux(ZnS)1-x thin films were deposited on glass substrate using thermal evaporation technique by varying the Cu concentration (x = 0.01, 0.02, 0.03, 0.05, 0.10 and 0.25). The prepared thin films were characterized using XRD, FE-SEM, EDS and UV–Vis spectroscopy. The X-ray diffraction studies revealed that the films are crystalline in nature and well oriented along (111) direction with the cubic crystal structure. Crystallite size increases with increase in Cu concentration. FE-SEM studies showed that the films are homogenous and pin-hole free. All the films exhibited p-type conductivity. It was also observed that the band gap of the Cux(ZnS)1-x films vary from 3.48 eV to 2.60 eV when the copper content varies from 0 to 0.25. At a Cu concentration of x = 0.03, the hole conductivity increases to 1.9 × 103 S/m retaining an optical transparency of ?73% in the visible spectra. This combination of optical transparency and hole conductivity of Cux(ZnS)1-x thin films for such low Cu concentration is, to our knowledge, the best reported to date. © 2018Item Enhanced thermoelectric power of Al and Sb doped In 2 Te 3 thin films(Elsevier Ltd, 2019) Vallem, V.; Bangera, K.V.; G.k, S.Aluminium and antimony are used as dopants for In 2 Te 3 to study their influence on the thermoelectric power of the films. Both aluminium and antimony are expected to replace indium in the film and contribute to the structural, electrical and thermoelectric behaviour of indium telluride. It is observed that addition of both Al and Sb dopants induced an additional phase of free Te. The electrical conductivity of In 2 Te 3 films is observed to reduce with Al doping and increase with Sb doping when compared with the electrical conductivity of un-doped films. The thermoelectric power is found to be maximum for 2.1% Al doped and 1% Sb doped films. Moreover, the thermoelectric power factor of In 2 Te 3 films is found to be enhanced 3.1 times for 2.1% doping of Al and 8.7 times for 1% Sb doping. © 2019 Elsevier Ltd