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Author: search.filters.author.Gaewdang, ThitinaiSubject: search.filters.subject.Hall effect

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    Processing and characterization of amorphous copper oxide thin films prepared by reactive magnetron sputtering
    (2018-01-01)
    Gaewdang, Thitinai
    ;
    Wongcharoen, Ngamnit
    In this paper, copper oxide (CuO<inf>x</inf>) thin films with amorphous phase were prepared on glass substrates by reactive dc magnetron sputtering. The influence of the flow rate of O<inf>2</inf> on the structural, optical and electrical properties of the as-deposited films was systematically studied. XRD revealed that the as-deposited films remained amorphous in the whole range of adjusted oxygen flow rate. Surface morphology and nanoparticle size of the films were observed by AFM. Electrical resistivity and Hall effect measurements were performed on the films with van der Pauw configuration. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. From temperature-dependent electrical conductivity of the films prepared at R(O<inf>2</inf>) of 1.5 sccm, it was show that three types of behavior can be expected, nearest-neighbor hopping at high temperature range (200-300 K), the Mott variable range hopping at low temperature (110-190 K) and Efros-Shklovskii variable range hopping at very low temperature (65-100 K). Some important parameters corresponding to Mott-VRH and ES-VRH like density of localized states near the Fermi level (N(E<inf>F</inf>)), localization length (ξ), degree of disorder(T<inf>0</inf>), hopping distance (R) and hopping energy (W) were determined. These parameters would be helpful for optimizing the performance of photovoltaic applications.
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    Influence of annealing temperature on the properties of SnS thin films prepared by vacuum thermal evaporation
    (2017-01-01)
    Wongcharoen, Ngamnit
    ;
    Gaewdang, Thitinai
    SnS thin films were deposited by thermal evaporation in vacuum on glass slide substrate. The as-deposited films were thermally annealed in a controlled N<inf>2</inf> atmosphere with annealing temperature in the range 100-500°C for 30 min. XRD, AFM, UV-VIS transmittance, FTIR and Hall effect measurements were used for characterization the as-deposited and annealed films. Based on the XRD patterns, the as-deposited and annealed films were indentified as the orthrombic structure. The band gap was found to increase from 1.15 to 1.42 eV when the annealing temperature increased from 100 to 500°C. The lowest resistivity and highest carrier concentration values were observed to be 12.95 Ω. cm and 1.98×10<sup>16</sup>cm<sup>-3</sup>on the films annealed at 100 and 200°C, respectively.