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Author: search.filters.author.Siriwongrungson, VilailuckSubject: search.filters.subject.HFCVD

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    Influence of thickness of p-type diamond Hall sensors synthesized by HFCVD on their response sensitivity to magnetic field
    (2018-07-02)
    Panyalert, Wasin
    ;
    Siriwongrungson, Vilailuck
    ;
    Suwanna, Prapakron
    ;
    Titiroongruang, Wisut
    ;
    Niemcharoen, Surasak
    This article presents the study of the influence of thickness of p-type diamond Hall sensors, which were synthesized by HFCVD, on their response sensitivity to magnetic field. Boron was added in ethyl alcohol as the reactant to obtain p-type diamond film at B/C ratio of 10,000 ppm. The synthesis durations of 6, 12 and 36 hours at the substrate temperature of 750°C were selected to achieve the required diamond film thicknesses of 50, 100 and 150 µm, respectively. The synthetic diamond films were confirmed to be diamond using Raman spectroscopy and the cross sections were analyzed using SEM (Scanning Electron Microscopy). Then, simple p-type diamond Hall sensors were fabricated using four silver electrodes adhered on the diamond film. The ohmic of the electrodes were confirmed by the measurement of electrical properties of electrodes and magnetic field response at three different diamond thicknesses. The response sensitivity to magnetic field were 12, 9 and 6 µV/Gauss, respectively. When the thickness of the p-type diamond Hall sensor increased, the response sensitivity to magnetic field decreased.
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    The study of P-type and N-type diamond crystals synthesis by hot filament chemical vapor deposition
    (2017-11-03)
    Sodngam, Piyachat
    ;
    Niemcharoen, Surasak
    ;
    Titiroongraung, Wisut
    ;
    Siriwongrungson, Vilailuck
    This research proposes the hot filament chemical vapor deposition (HFCVD) for synthesis of p-type and n-type diamond by doping of boron trioxide (B<inf>2</inf>O<inf>3</inf>) and phosphorous pentoxide (P<inf>2</inf>O<inf>5</inf>) in ethyl alcohol (C<inf>2</inf>H<inf>5</inf>OH), respectively. The synthesis was conducted for 180 h with annealing under hydrogen atmosphere every 60 h to improve the quality of the diamond. Composition of the synthetic diamond was analyzed using energy-dispersive x-ray spectroscopy (EDX). The main composition of the synthetic diamond is boron and carbon, and phosphorous and carbon for boron-doped and phosphorous doped synthetic diamond crystal, respectively. The crystal size and physical characteristics were analyzed using scanning electron microscopy (SEM). The synthetic diamond as large as 1.56 mm and 1.63 mm was synthesized. In addition, the synthetic diamond was confirmed to be diamond using Raman spectroscopy. The peak at Raman shift of 1332 cm<sup>-1</sup> that is the same as the natural diamond was observed. Moreover, electrical properties of the synthetic diamond were compared with intrinsic diamond at similar crystal size. The conductivity of the boron-doped synthetic diamond shown positive side (p-type) and phosphorous-doped synthetic diamond shown negative side (n-type) from the measurement using hot probe. The resistance of the synthetic doped with B<inf>2</inf>O<inf>3</inf> and P<inf>2</inf>O<inf>5</inf> is 5.711 kΩ and 4.570 kΩ, respectively from the measurement using Circuit applied for current and voltage measurement. The resistances measured are significantly lower than intrinsic diamond. Therefore, it can be implied that the conductivity of the synthetic diamond is better than intrinsic diamond.
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    The Study of Fabricated N-Type Diamond for Hall Sensor by Hot Filament Chemical Vapor Deposition (HFCVD) Method
    (2017-01-01)
    Chanthep, Prasert
    ;
    Panyalert, Wasin
    ;
    Siriwongrungson, Vilailuck
    ;
    Atiwongsangthong, Narin
    ;
    Titiroongraung, Wisut
    In this research, the study of fabricated n-type diamond for Hall sensor by hot filament chemical vapor deposition (HFCVD) method is presented. The fabricated n-type diamond film doped with phosphorus in ethanol (C2H5OH) at P/C ratio of 10,000 ppm was synthesis on silicon substrate at 750 °C for 12 hours. Its morphology, crystallinity and types of carbon were analyzed using optical microscope and Raman spectroscope. The structure of n-type diamond for Hall Sensor comprises of four silver paste electrodes on the surface of the fabricated n-type diamond film. An electrical property of electrode, Ohmic, was tested on the fabricated silver paste electrodes. The impact of temperature on the fabricated n-type diamond for Hall sensor was evaluated. The operating temperature as high as 240 °C was observed. Magnetic response characteristic of the fabricated n-type diamond was measured. The absolute sensitivity of 9 µV/Gauss was observed. Properties of the fabricated n-type diamond for Hall sensor under operation were measured. The electrical density is 1.82 x 10<sup>15</sup> cm<sup>-3</sup>, electrical resistance is 5.443 ?·cm and electrical mobility is 630 cm<sup>2</sup>/v-sec.