Somjaijaroen, Natthawirot

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Somjaijaroen, Natthawirot
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Somjaijaroen, N.
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natthawirot.so@kmitl.ac.th

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    Item type:Publication,
    Simultaneous O2 plasma and thermal treatment for improved surface conductivity of Cu-Doped SnO2 films
    (2019-08-01)
    Somjaijaroen, Natthawirot
    ;
    Sakdanuphab, Rachsak
    ;
    Chanlek, Narong
    ;
    Chirawatkul, Prae
    ;
    Sakulkalavek, Aparporn
    Cu-doped SnO<inf>2</inf> thin films were deposited on a glass substrate using radio frequency magnetron sputtering. The effects of varying the O<inf>2</inf> partial pressure during the deposition process and post-O<inf>2</inf> plasma treatment at 420 °C were investigated. Bulk and surface oxidation states were measured by X-ray absorption near-edge structure spectroscopy and X-ray photoelectron spectroscopy. The as-deposited films exhibited oxygen deficient compositions and Cu<sup>+</sup> or Cu<sup>2+</sup> ions, which depend on the deposited O<inf>2</inf> partial pressure. After the post-plasma treatment, the films changed from an amorphous structure into a low crystalline film. X-ray diffraction results indicated substitutional doping, wherein some Sn<sup>4+</sup> ions were replaced with Cu<sup>+</sup> or Cu<sup>2+</sup> ions. The O<inf>2</inf> plasma treatment can remove Cu<sup>2+</sup> and O<sup>2−</sup> from the film surface. The oxygen deficiency defects and Cu<sup>+</sup>- or Cu<sup>2+</sup>- doped present at the surface are the key factors in controlling the sheet resistance of the Cu-doped SnO<inf>2</inf> film. The minimum sheet resistance was obtained after the plasma treatment of the films deposited at a 2% O<inf>2</inf> partial pressure.
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    Item type:Publication,
    Improved Transparent Gas Sensor Properties of Cu-Doped SnO2 Films using O2 Plasma Treatment
    (2019-09-16)
    Somjaijaroen, N.
    ;
    Sakdanuphab, R.
    ;
    Sakulkalavek, A.
    Cu-doped SnO<inf>2</inf> films were deposited on glass slide substrate using an RF magnetron sputtering method. The effects of O<inf>2</inf> partial pressures in the deposition process and post O<inf>2</inf> plasma treatment were assessed for optical and sensing properties. O<inf>2</inf> partial pressures from 2% to 10% were assessed. Post-plasma treatment used a 15 mL/min O<inf>2</inf> flow, 450 °C annealing temperature and 30 min treatment time. Optical transmission spectra showed that the films deposited at higher O<inf>2</inf> partial pressures had higher transparency and increased band gaps from 3.08 to 3.78 eV. After O<inf>2</inf> plasma treatment, the films showed better than optical transmission. However, when the O<inf>2</inf> partial pressure increased to 10%, the optical transmission declined slightly because the film had higher surface roughness, smaller crystals and fewer oxygens in the parent rutile tetragonal cells, enhanced the sensor response at room temperature.