2. Articole

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Author: search.filters.author.Korotcenkov, GhenadiiSubject: search.filters.subject.thin film

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    Thermal transport evolution due to nanostructural transformations in ga-doped indium-tin-oxide thin films [Articol]
    (2021) Cocemasov, Alexandr; Brinzari, Vladimir; Jeong, Do-Gyeom; Korotcenkov, Ghenadii; Lee, Jong S.; Nika, Denis L.
    We report on a comprehensive theoretical and experimental investigation of thermal con- ductivity in indium-tin-oxide (ITO) thin films with various Ga concentrations (0–30 at. %) deposited by spray pyrolysis technique. X-ray diffraction (XRD) and scanning electron microscopy have shown a structural transformation in the range 15–20 at. % Ga from the nanocrystalline to the amorphous phase. Room temperature femtosecond time domain thermoreflectance measurements showed nonlinear decrease of thermal conductivity in the range 2.0–0.5 Wm−1 K−1 depending on Ga doping level. It was found from a comparison between density functional theory calculations and XRD data that Ga atoms substitute In atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The calculated phonon dispersion relations revealed that Ga doping leads to the appearance of hybridized metal atom vibrations with avoided-crossing behavior. These hybridized vibrations possess shortened mean free paths and are the main reason behind the thermal conductivity drop in nanocrystalline phase. An evolution from propagative to diffusive phonon thermal transport in ITO:Ga with 15–20 at. % of Ga was established. The suppressed thermal conductivity of ITO:Ga thin films deposited by spray pyrolysis may be crucial for their thermoelectric applications.
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    Plasma treatment and surface sensibilization of tin dioxide films for enhancement of gas sensitivity [Articol]
    (2005) Brînzari, Vladimir; Dmitriev, Serghei; Korotcenkov, Ghenadii
    This paper presents result of investigation aimed at the improvement of gas sensitive properties of SnO2 thin film gas sensors (TFGS) by means of high frequency (HF) oxygen plasma treatment and its surface doping. Used in experiments SnO2 films were deposited by spray pyrolysis method. It is shown that plasma treatment provides 3-4 times growth of thin film gas sensitivity. Surface doping of SnO2 films with Pd leads to gas sensitivity increasing by order. It is conluded that combination of HF oxygen plasma treatment and surface sensibilization through surface doping is an effective way to considerable improvement of gas sensitive properties of tin dioxide based TFGS.