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    Impressive Response of Spin-Coated ZnO Nanoparticle UV-Sensitive Devices with Various Thicknesses under Different UV Intensities
    (2021-09-01)
    Pawong, Whongsatorn
    ;
    Wasapinyokul, Kamol
    We fabricated ultraviolet (UV) detectors based on spin-coated pure zinc oxide (ZnO) nanoparticles with a metal–semiconductor–metal configuration. Devices with various ZnO layer thicknesses were characterized under different UV intensities, and their responsivity, sensitivity, response time, and recovery time analyzed. The following performance was achieved: responsivity of 99.8 A W<sup>−1</sup>, sensitivity of 531.1, and response and recovery times of 0.01 s and 0.07 s, respectively. Increasing the thickness revealed monotonic effects on each property: the responsivity decreased, the sensitivity decreased, and the response and recovery times increased, mainly because of the thin penetration depth of ZnO and the lengthened cracks on the thicker layer. However, the effects of the UV intensity on the parameters were not monotonic. Indeed, as the intensity was increased, the responsivity decreased, the sensitivity first increased then decreased, the response time first increased before shortening, while the recovery time consistently shortened. Such trends resulted from the combination of several mechanisms: shrinkage of depletion layers, saturation of excitons, and saturation of trapping states. Increasing the radiation-on time shortened both the response and recovery times. This device performance is impressive compared with devices with more complicated material formats, device structure, or fabrication methods. Some complications in the work are also discussed.
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    Enhanced silicon bandgap by platinum diffusion for UV detector
    (2013-03-01)
    Ueamanapong, Surada
    ;
    Srithanachai, Itsara
    ;
    Atiwongsangtong, Narin
    ;
    Klunngien, Nipapan
    ;
    Poyai, Amporn
    This research article proposes a new method that enables silicon to respond to light in the UV wavelength range by doping Platinum (Pt), which is an impurity atom, into silicon. It is widely recognized that silicon semiconductor can respond to visible light. Silicon photodetector can thus detect merely the light with wavelengths of visible light and near IR. The effect of Pt on photocurrent of a metal-semiconductor-metal (MSM) photodetector was investigated. The undoped and Pt-doped silicon photodetectors in this experiment were fabricated to test the current characteristics. It was found that Pt-doped photodetectors can respond to the light wavelength of 365 nm. The energy bandgap (E<inf>g</inf>), a parameter related to the optical response of semiconductor, of Pt-doped silicon was obtained by extracting from Arrhenius plot of generation current of silicon p-n junction. The result was shown that E<inf>g</inf> of Pt-doped silicon is increased with the introduction of Pt. E<inf>g</inf> of silicon is typically 1.12 eV; however, the E<inf>g</inf> in this study is approximated at 1.7 eV. © 2013 American Scientific Publishers All rights reserved.
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    MSM diamond UV detector
    (2011-10-04)
    Cheirsirikul, S.
    ;
    Jesen, S.
    ;
    Hruanun, C.
    Development Synthesizing Diamond film on (100) silicon substrate was processed by HFCVD (Hot Filament Chemical Vapor Deposition). The processes consisted of using methane (CH4) to produce intrinsic diamond and then constructing MSM device on the diaphragm of diamond film. Schotthy junctions on the top and the lower of the diaphragm were produced by aluminum which caused the carriers were able to move in the vertical direction to reduce the effect of grain boundaries. Then, the spectral response was investigated for the light wavelength in the range of 190 nm to 800 nm. The results showed that the device had good response to UV light and very low response to visible light. After that the device was sintered at 450OC in different times in order to find the decreased leakage current and proper response time. © 2011 IEEE.
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    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.