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Author: search.filters.author.Kianwimol, SupasakSubject: search.filters.subject.DC sputtering

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    Effect of annealing temperature on thermoelectric properties of bismuth telluride thick film deposited by DC magnetron sputtering
    (2020-07-15)
    Kianwimol, Supasak
    ;
    Sakdanuphab, Rachsak
    ;
    Chanlek, Narong
    ;
    Harnwunggmoung, Adul
    ;
    Sakulkalavek, Aparporn
    We report the thermoelectric properties of thick bismuth-telluride (Bi<inf>2</inf>Te<inf>3</inf>) films deposited on polyimide substrates by DC magnetron sputtering and annealed at various temperatures (150–350 °C). The influence of annealing temperature on the microstructure and electronic structure of thick Bi<inf>2</inf>Te<inf>3</inf> films is discussed. In this work, the annealed film at 250 °C has the best thermoelectric property due to highest electrical conductivity and Seebeck coefficient. The main effect of annealing temperature was really helpful to improve crystalline structure and enhance carrier mobility, whereas the carrier concentration was reduced due to the volatile of tellurium atom during annealing. Chemical states of bound and unbound atoms (Bi, Bi<sup>3+</sup>, Te, and Te<sup>2‐</sup>) on the surface play an important role in electrical properties. The exceed temperature caused the micro-crack formation and affect carrier transport by the scattering. The power factor of Bi<inf>2</inf>Te<inf>3</inf> deposited by DC magnetron sputtering and annealed at 250 °C is comparable to the power factors of thick Bi<inf>2</inf>Te<inf>3</inf> film deposited by various deposition techniques. The output power of single-leg, thick, thermoelectric Bi<inf>2</inf>Te<inf>3</inf> film annealed at 250 °C as a function temperature generated a power of 0.98 μW at a temperature difference of 50 °C.
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    Experimental Study on Flexible Bismuth Telluride Thin Films Deposited by DC Sputtering at Different Powers
    (2019-06-15)
    Kianwimol, Supasak
    ;
    Wanarattikan, Pornsiri
    ;
    Sakdanuphab, Rachsak
    ;
    Pluengphon, Prayoonsak
    ;
    Bovornratanaraks, Thiti
    Bismuth telluride (Bi <inf>2</inf> Te <inf>3</inf> ) thin films have been deposited onto polyimide sheet substrates by direct-current (DC) magnetron sputtering at different powers and their microstructure, composition, and electrical and thermoelectrical properties studied. The experimental results indicated that the sputtering power was the key parameter determining their thermoelectric properties. X-ray diffraction analysis confirmed the highly (015) preferred orientation of the films. The Te content and grain size depended on the sputtering power. The power factor of Bi <inf>2</inf> Te <inf>3</inf> deposited by DC sputtering at power of 60 W was comparable to that obtained for highly (00l) Bi <inf>2</inf> Te <inf>3</inf> thin film.
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    Simultaneous stoichiometric composition and highly (00l) orientation of flexible Bi2Te3thin films via optimising the DC magnetron sputter-deposition process
    (2019-01-30)
    Somdock, Nuttakrit
    ;
    Kianwimol, Supasak
    ;
    Harnwunggmoung, Adul
    ;
    Sakulkalavek, Aparporn
    ;
    Sakdanuphab, Rachsak
    Simultaneous stoichiometric composition and highly (00l) orientation of flexible Bi<inf>2</inf>Te<inf>3</inf> thin films were investigated under the DC magnetron sputtering parameters. Stoichiometric Bi<inf>2</inf>Te<inf>3</inf> and highly (00l) orientation structure was obtained by sputtering conditions, preheat temperature at 350 °C, and working pressure of 1.8 × 10<sup>−3</sup> mbar. This designed structure of layered compact feature with stoichiometry provide the relatively high mobility. The maximum carrier mobility of 118 cm<sup>2</sup>/V was observed for highly (00l) film. The electrical conductivity of thin film has been greatly enhanced, to a maximum of about 14.90 × 10<sup>3</sup> S/cm at 50 °C. This value is higher than those of hot-pressed or spark plasma sintering n-type Bi<inf>2</inf>Te<inf>3</inf> bulk alloys. The maximum power factor of 12.5 × 10<sup>−3</sup> W/m.K<sup>2</sup> was obtained at 300 °C.
      1