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Start date: 2020Subject: search.filters.subject.DC magnetron sputtering

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    Advances in flexible telluride thin-film thermoelectric generators: Deposition, performance, and module fabrication
    (2026-04-01)
    Theekhasuk, Nattharika
    ;
    Sakdanuphab, Rachsak
    ;
    Kianwimol, Supasak
    ;
    Khumtong, Thanakorn
    ;
    Toan, Nguyen Van
    Flexible thermoelectric generators (TEGs) are gaining increasing attention for wearable and skin-attachable electronics due to their ability to harvest low-grade heat from the human body. In this work, p-type Sb<inf>2</inf>Te<inf>3</inf> and n-type Bi<inf>2</inf>Te<inf>3</inf> thin films were deposited by direct current (DC) magnetron sputtering, and the effects of post-deposition annealing on their structural, electrical, and thermal transport properties were systematically evaluated. X-ray diffraction revealed that n-Bi<inf>2</inf>Te<inf>3</inf> exhibited higher crystallinity than p-Sb<inf>2</inf>Te<inf>3</inf>, attributed to its lower formation energy. Annealing at 250 °C markedly enhanced the electrical conductivity of both films, with p-Sb<inf>2</inf>Te<inf>3</inf> showing a larger improvement due to concurrent increases in carrier concentration and mobility driven by Te volatilization and the formation of acceptor-type vacancies and antisite defects. In contrast, n-Bi<inf>2</inf>Te<inf>3</inf> exhibited a slight reduction in carrier concentration as a result of compensating donor defects. Consequently, maximum ZT values of approximately 0.5 for p-Sb<inf>2</inf>Te<inf>3</inf> and 0.25 for n-Bi<inf>2</inf>Te<inf>3</inf> were achieved at 513 K. Notably, the compatibility factor (S) values of both films differed by less than a factor of two, indicating favorable thermodynamic pairing for p–n module assembly. A flexible TEG module with 12 thermocouples was subsequently fabricated and delivered an output power of 0.65 μW at ΔT < 25 K, demonstrating promising potential for scalable self-powered wearable electronics.
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    Influence of Sputtering Power Density on the Thermoelectric and Mechanical Properties of Flexible Thermoelectric Antimony Telluride Films Deposited by DC Magnetron Sputtering
    (2020-05-01)
    Junlabhut, Prasopporn
    ;
    Nuthongkum, Pilaipon
    ;
    Sakdanuphab, Rachsak
    ;
    Harnwunggmoung, Adul
    ;
    Sakulkalavek, Aparporn
    Antimony telluride (Sb<inf>2</inf>Te<inf>3</inf>) films were deposited on flexible polyimide substrates by DC magnetron sputtering technique using a 99.9% alloy Sb<inf>2</inf>Te<inf>3</inf> target. We measured structural, electrical, thermoelectric and mechanical properties with sputtering power density in the range 30–50 W. X-ray diffraction confirmed that all Sb<inf>2</inf>Te<inf>3</inf> films have high crystallinity with a significant preferential growth along the (015) plane. Surface morphologies were verified by scanning electron microscope: deposited film grain size increased with sputtering power density. The elemental composition was determined by energy dispersive x-ray spectroscopy. Electrical transport properties, carrier concentration, was measured by Hall effect measurement at room temperature. Electrical conductivity and Seebeck coefficient were simultaneously measured by a DC four-terminal method (ZEM-3). The power factor was strongly dominated by electrical conductivity, leading to a maximum of 1.95 mW/K<sup>2</sup>m with sputtering power 45 W at 300°C. The wettability test, based on the contact angle, evaluated surface energy and hydrophilicity. Nanoindentation was measured on a NHT<sup>2</sup> CSM Instrument with diamond Berkovich indenter (B-P 31) at room temperature. The hardness and elastic modulus of deposited Sb<inf>2</inf>Te<inf>3</inf> films increased with the power density.
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    Enhancing the thermoelectric properties of sputtered Sb2Te3 thick films via post-annealing treatment
    (2020-04-15)
    Junlabhut, Prasopporn
    ;
    Nuthongkum, Pilaipon
    ;
    Sakulkalavek, Aparporn
    ;
    Harnwunggmoung, Adul
    ;
    Limsuwan, Pichet
    Sb<inf>2</inf>Te<inf>3</inf> films of more than 10 μm in thickness were deposited on flexible polyimide substrates by heat treatment-assisted DC magnetron sputtering. The post-annealing parameters including the temperature (150–350 °C) and time (15–60 min) were varied to investigate the microstructure, chemical composition, porosity and thermoelectric properties of the thick films. X-ray diffraction showed that both the as-deposited and post-annealed films were polycrystalline with significant preferential growth along the (015) plane. The films showed slightly off-stoichiometric compositions after post-annealing treatment. Increasing the annealing temperature and annealing time led to an increase in crystalline size and a decrease in porosity of the thick films. This was related to grain growth, agglomeration and surface improvement. The electrical transport and thermoelectric properties including carrier concentration, carrier mobility, electrical conductivity and Seebeck coefficient were investigated using Hall effect measurements and a ZEM-3 apparatus. A maximum power factor of 1.7 mW/K<sup>2</sup>m was obtained following annealing at 350 °C for 30 min.
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    Effect of sputtering power on optical properties of nickel oxide electrochromic thin films
    (2020-01-01)
    Panprom, P.
    ;
    Sritonwong, P.
    ;
    Limwichian, S.
    ;
    Eiamchai, P.
    ;
    Patthanasettakul, V.
    The preparation and characterization of nickel oxide (NiO) thin film for electrochromic smart window applications are studied. The NiO thin film was prepared by the DC magnetron sputtering from a pure nickel target. The sputtering power was varies in the interval 50–200 W. The crystallinity and physical morphology of NiO films are characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The XRD result revealed that polycrystalline NiO thin films with preferred growth directions along (111) and (200) planes are obtained. Moreover, the electrochromic property of NiO thin films was investigated with a UV-Visible spectrophotometer. The colored state of the electrochromic cell was obtained by the ion insertion at the 1-V external applied bias in 0.1 M KOH. The reversibility between the colored and bleached states is confirmed by the optical transmittance. The result shows the optical contrast as high as 28.68.