Now showing 1 - 10 of 15
  • Some of the metrics are blocked by your 
    Item type:Publication,
    The innovative AlN-ISFET based pH sensor
    (2008-10-06)
    Bunjongpru, W.
    ;
    Porntheeraphat, S.
    ;
    Trithaveesak, O.
    ;
    Somwang, N.
    ;
    Khomdet, P.
    This innovative pH-ISFET sensor used nanocrystalline-AlN thin film as ion-sensitive membrane which prepared by reactive gas-timing r.f, magnetron sputtering without heating substrate and post annealing. The technique of gas-timing r.f. magnetron sputtering purposed by us, the feeding gas is on-off controlled periodically in such a way that the deposited AlOxNy film has a quite stable composition of aluminum, nitrogen and oxygen (A1:O:N=52:18:30 %) all over the entire film. The AlN-ISFET devices were structured. The pH-sensitivity characteristics show increasing sensitivity depended on film thickness. The highest sensitivity is 54.50 mV/pH achieved from 80 nm of AlN thin film which is comparable to our previous report Si<inf>3</inf>N<inf>4</inf>-ISFET devices. © 2008 IEEE.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    UV-enhanced photodetector with nanocrystalline-TiO 2 thin film via CMOS compatible process
    (2011-12-01)
    Bunjongpru, W.
    ;
    Panprom, P.
    ;
    Porntheeraphat, S.
    ;
    Meananeatra, R.
    ;
    Jeamsaksiri, W.
    This research presents nanocrystal titaniumdioxide (nanocrystal-TiO <inf>2</inf>) film deposition technique with CMOS compatible process [1] to extend the optical response bandwidth of silicon based photodetecting devices toward ultraviolet range [2]. The thin films were initially deposited as Titanium Nitride (TiN) using DC magnetron reactive sputtering system. It was then annealed under nitrogen atmosphere at 800°C. After analyzing crystal structures and surface morphology with X-ray diffraction and FE-SEM systems, it was found that the deposited thin films showed the crystal phase of TiO <inf>2</inf> oriented along (200) plane of Rutile crystal structure with 50 nm grain size and increasing with film thickness. Using electroreflectance (ER) spectroscopy measurement [3], the bandgap of nanocrystal-TiO <inf>2</inf> was revealed to be 3.16 eV. PN-heterojunction photodiodes were fabricated with Nanocrystal-TiO <inf>2</inf>/SiO <inf>2</inf>/p-Si structures. Interdigitated aluminum structures were used as electrodes. By varying the thickness of nanocrystal-TiO <inf>2</inf> film, i.e. 30, 60, and 90 nm, the devices could response further into the UV range. The absorption edge wavelength investigated by photoresponse measurement was at 275 nm and shifting to the shorter wavelength as a function of the nanocrystal-TiO <inf>2</inf> grain size due to quantum confinement phenomenon [4]. The nanocrystal-TiO <inf>2</inf>/SiO <inf>2</inf>/p-Si photodetector had dark current = 5.31nA (2V), photocurrent = 0.9 uA, rise time = 58 us, fall time = 47 us at 30 nm thickness of TiO <inf>2</inf>. © 2011 IEEE.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Photoreflectance study of AIN thin films grown by reactive gas-timing rf magnetron sputtering
    (2002-11-20)
    Kietipaisalsophon, N.
    ;
    Bunjongpru, W.
    ;
    Band-gap energy of AIN thin films was investigated by room-temperature photoreflectance (PR) spectroscopy. Using rf magnetron sputtering, the reactive gas-timing technique was successfully applied to grow cubic-AIN thin films. The define XRD patterns of all deposited films show orientation of cubic structure in (111) and (200) planes. The PR spectra clearly exhibit a band-gap energy of cubic-AIN depending on the flow rate of N<inf>2</inf> gas. The band-gap transition energies were determined by fitting the PR spectra to theoretical line-shape expression. The band-gap transition energies decreased with increasing flow rate of N<inf>2</inf>.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    A disposable polydimethylsiloxane microdevice for DNA amplification
    (2010-02-05)
    Lekwichai, A.
    ;
    Porntheeraphat, S.
    ;
    Bunjongpru, W.
    ;
    Sripumkhai, W.
    ;
    Supadech, J.
    In this study, we demonstrate the disposable polydimethylsiloxane (PDMS) microchip provided for DNA amplification. The device consists of two main parts. The first part is PDMS/glass stationary chamber, the other part is a temperature-control microdevice on SiO<inf>2</inf>/Si substrate. This device consists of a thin film Pt-microheater and a Pt-temperature sensor, which were fabricated with CMOS compatible process. The performance of the device in the DNA amplification shows that, with 10 μl of PCR mixture volume, the approximately 700 bp DNA were successfully amplified within 50 minutes by 30 PCR cycles. The amplified products were comparable with those of a conventional method using electrophoresis. The PCR chip is also suitable for mass production. © (2010) Trans Tech Publications.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Oxygen gas-timing control for variety properties of sputtered-ZnO
    (2010-02-05)
    Limwichean, K.
    ;
    Porntheeraphat, S.
    ;
    Bunjongpru, W.
    ;
    Panprom, P.
    ;
    Pankiew, A.
    In this report, we present sputtered zinc oxide (ZnO) thin films grown with different argon (Ar) and oxygen (O<inf>2</inf>) gas-timing sequence. Metallic zinc (Zn) with 5N-purity was used as a sputtering target, while Ar and O <inf>2</inf> of 6N-purity were used as the bombard and reactive gases, respectively. The crystalline orientation, surface morphology, chemical composition, optical and electrical properties of deposited ZnO thin films were determined by XRD,AFM and UV-VIS measurement, respectively. The XRD result implied that deposition ZnO thin films at different O<inf>2</inf> gas-timing control corresponded to the (002) plane of hexagonal ZnO structure at 2θ = 34.4°. Furthermore, when the reactive time of O<inf>2</inf> was increased, the transmittance of ZnO thin films exhibited the energy gap increase from ∼2.95 to ∼3.18 eV, whereas the surface roughness was found to decrease. Finally, ZnO thin films were oxidized after the deposition. © (2010) Trans Tech Publications.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Application of double gate ion sensitive field effect transistor for detection of fluid flow rate in micro-channel
    (2010-02-05)
    Jiemsakul, T.
    ;
    Trithaveesak, O.
    ;
    Bunjongpru, W.
    ;
    Hruanun, C.
    ;
    Poyai, A.
    In this work a micro flow sensor, using a double gate Ion Sensitive Field Effect Transistor (ISFET) and two metal electrodes, for fluid flow rate measurement in micro-channels were fabricated and demonstrated. By the channel fabrication the molds were patterned reversely on a silicon wafer using Deep Reactive Ion Etcher (DRIE). The double gate ISFET and two metal electrodes were placed on the mold in the distance 15 millimeters. The channels were formed using polydimethylsiloxane (PDMS) from the mold with the width 1000 and 2000 micrometer and the depth of 250 micrometer. After removing PDMS from the mold the channel was bonded with glass substrate by RF plasma technique. By the verification of flow sensors working range water and one mole of sodium nitrate solution were alternated in flow channel. The fluid flow rate were compared with the flow rate from weighing. It found from the comparison that the high deviation was found at low flow rate. Furthermore, the deviation depends also on the dimension of the flow channel. © (2010) Trans Tech Publications.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    High-dielectric constant AlON prepared by RF gas-timing sputtering for high capacitance density
    (2008-10-01)
    Poyai, A.
    ;
    Bunjongpru, W.
    ;
    Klunngien, N.
    ;
    Porntheerapat, S.
    ;
    Hruanan, C.
    This paper presents the method to prepare and characterize high-dielectric constant aluminum oxynitride (AlON) formed by RF gas-timing sputtering. AlON layers of 725 nm have been prepared on metal-dielectric-metal structure with substrate temperature below 100 °C. Capacitance versus bias voltage has been measured. The dielectric constant of AlON has been calculated from the slope of the plot of capacitance versus capacitor area. The value of 11 has been obtained from this study. This depends on the composition of the AlON material, which is analyzed by Auger electron spectroscopy. © 2008 Elsevier Ltd. All rights reserved.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Tantalum oxide bio-photonics thin film grown by gas-timing innovation technique
    (2013-09-18) ;
    Porntheeraphat, S.
    ;
    Horprathum, M.
    ;
    Chananonnawathorn, C.
    ;
    Bunjongpru, W.
    Tantalum oxide (TaxOy) as high refractive index material has been grown on p-type silicon and quartz substrates by R.F. magnetron sputtering with our innovative technique called "reactive-gas timing". The reactive gas timing technique is an on-off time period sequence between argon (Ar) and oxygen (O2) plasma during sputtering process. The technique of gas-timing plays the effect on the properties of TaxOy thin film. The bombarded Ar-plasma was varied at 2, 5 and 8 sec, while the period of reactive O2-plasma was kept at 5 sec in this experiment. The physical and optical properties were investigated by using X-ray diffraction (XRD), Atomic Force Microscope (AMF), UV-Visible spectrometer and Spectroscopic Ellipsometer, respectively. The XRD spectra and AFM photographs show all films are amorphous phase with smooth feature. Meanwhile the transmittance of sputtered thin film decreases with 10% and the absorption edge shifts to lower energy with the increasing of the argon period from 2 sec to 8 sec. The refractive index as showed by ellipsometry slightly increases from 2.08 to 2.17 at wavelength 550 nm with the increasing of argon period from 2 sec to 8 sec. The increasing of the refractive index might dues to tantalum (Ta) rich which consists in thin films. The Ar-plasma period in the deposited film plays an important role on the properties of the TaxOy thin films especially as optical refractive index material. © 2013 SPIE.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Nanocrystal-ZnO thin film deposition by a novel reactive gas-timing RF magnetron sputtering provided for UV photodetectors
    (2010-02-05)
    Panprom, P.
    ;
    Porntheeraphat, S.
    ;
    Bunjongpru, W.
    ;
    Tiwawong, T.
    ;
    Yamwong, W.
    The fabrication and characterizations of nanocrystal-ZnO thin film used as active layer of MSM-photodetector structure are reported. The ZnO thin film were successfully sputtered on SiO<inf>2</inf>/Si substrates without heating or annealing processes by using a novel reactive gas-timing technique. In our experiment, the ZnO thin film properties with different gas-timing ratio of Ar/O<inf>2</inf> were investigated. For fabricating of UV detector, the Al interdigitate electrode was deposited on SiO<inf>2</inf>/Si substrate by DC sputtering process and ZnO thin film was deposited as active layer. The response wavelength peak occurs at around 380 nm corresponding to ZnO energy bandgap of 3.2 eV .The I-V measurements indicates the Schottky behavior of ZnO on Al contact. © (2010) Trans Tech Publications.
  • Some of the metrics are blocked by your 
    Item type:Publication,
    Non-enzymatic urea sensor using molecularly imprinted polymers surface modified based-on ion-sensitive field effect transistor (ISFET)
    (2016-11-25)
    Rayanasukha, Y.
    ;
    Pratontep, S.
    ;
    Porntheeraphat, S.
    ;
    Bunjongpru, W.
    ;
    A novel molecularly imprinted electrochemical sensor based on ISFET device has been developed for urea detection sensor. The molecularly imprinted polymers (MIPs) were prepared by photopolymerization on the surface of ISFET device using PMMA and urea as the functional polymer and molecular template, respectively. The fabricated sensors were characterized by potentiometry and UV-Vis spectroscopy. The preparation conditions were optimized for performance of the sensors, i.e. drop-cast volume and incubation time. The MIP modified ISFET sensors has linear range response from 1.0 × 10<sup>− 4</sup> to 1.0 × 10<sup>− 1</sup> M with the limit of detection of 1.0 × 10<sup>− 4</sup> M (S/N = 3). The MIP modified ISFET sensors also exhibit excellent reproducibility, repeatability and stability, as well as high selectivity to urea.