Browsing by Author "Vallem, V."

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    Effect of substrate temperature and film thickness on the thermoelectric properties of In2Te3 thin films
    (Elsevier Ltd, 2017) Vallem, V.; Bangera, K.V.; Shivakumar, G.K.
    Herein, the thermoelectric properties of vacuum deposited In2Te3 thin films were investigated by varying the substrate temperature and the thickness of the films. The thermo-electro motive force of the prepared films was found to increase with an increase in the substrate temperature up to 423 K and then decrease at 473 K due to the presence of mixed-phase structure. The maximum thermoelectric power of 220 ?V/K was observed for the films deposited at 423 K substrate temperature, which was found to decrease with increase in thickness. The films deposited at 423 K with 150 nm thickness showed maximum power factor of 27 ?Wm?1K?2 at 450 K. These observations are explained on the basis of structural, morphological and compositional changes. © 2017 Elsevier B.V.
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    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
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    Structural, electrical and optical properties of stoichiometric In2Te3 thin films
    (Elsevier Ltd, 2017) Vallem, V.; Bangera, K.V.; Shivakumar, G.K.
    In2Te3 thin films were grown by thermal evaporation technique. The annealing of films played a major role to obtain stoichiometry, regardless of substrate temperature. Annealing at 300 ?C resulted in well oriented, mono-phased and nearly stoichiometric In2Te3 thin films. The variation in grain size of In2Te3 films associated with the substrate temperatures provides a significant control over the resistivity of the films, and the resistivity decreased with an increase in the grain size. The activation energy and optical band gap of stoichiometric In2Te3 films were found to be 0.01±0.005 eV and 0.99±0.02 eV, respectively. The absorption co-efficient of these films was found to be of the order of 105 cm?1. © 2016 Elsevier Ltd and Techna Group S.r.l.
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    Synthesis of single-phase stoichiometric InTe thin films for opto-electronic applications
    (Academic Press, 2019) Vallem, V.; Bangera, K.V.; G.k, S.
    Mono-phased and stoichiometric InTe thin films were successfully prepared using vacuum evaporation technique. A systematic variation in substrate temperature and annealing temperature along with annealing duration resulted stoichiometric and single phase InTe films. The annealing treatment of as-deposited films resulted in the structural transformation from mixed phase of In 2 Te 3 and InTe to mono-phased InTe. The electrical conductivity of stoichiometric single phase films was found to be 15.612 ? ?1 cm ?1 . The optical band gap of stoichiometric InTe films was found to be 1.42 eV and absorption coefficient of the films was of the order of 10 6 cm ?1 . Electrical properties of mono-phased films accompanied with optical properties such as direct band gap and absorption coefficient makes them suitable for optoelectronic devices. © 2019 Elsevier Ltd