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Author: search.filters.author.Supadech, S.Subject: search.filters.subject.Photodetector

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    White noise due to photocurrents in planar MSM structures on low-resistivity Si
    (2003-10-01)
    Khunkhao, S.
    ;
    Niemcharoen, S.
    ;
    Supadech, S.
    ;
    Sato, K.
    The noise due to photocurrent at low frequencies (3-100 kHz) has been observed of planar aluminum/n-type silicon/aluminum (Al/n-Si/Al) structures based on low-resistivity silicon. It was found that these structures exposed to illumination showed much lower noise than the full shot noise above 5 kHz under a certain operating condition. If the current noise power spectrum is expressed as S(ω) = 2eI<inf>p</inf>Γ<sup>2</sup>, where e is the electronic charge and I<inf>p</inf> is the photocurrent, the noise ratio Γ<sup>2</sup> lies between 0.2 and 1.0, depending on the bias voltage. These results are attributed to the planar structures of the samples having wide electrode separation. Spatially uniform carrier generation due to illumination at the active surface and the decrease in the cross-correlation between the current components in the structure might be playing the key role to reduce the noise to lower levels than that of full shot noise under a certain operating condition. © 2003 Elsevier Ltd. All rights reserved.
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    UV photodetector from Schottky diode diamond film
    (2002-03-01)
    Thaiyotin, L.
    ;
    Ratanaudompisut, E.
    ;
    Phetchakul, T.
    ;
    Cheirsirikul, S.
    ;
    Supadech, S.
    Diamond film was synthesized on a silicon substrate by hot-filament CVD and used to fabricate a Schottky photodiode for the detection of UV light. This paper presents an improved structure of photodiode, which reduces the effect of grain boundaries in the polycrystalline diamond film. The Schottky photodiode was fabricated on free-standing diamond film and operation in a vertical direction can be expected to reduce the effect of grain boundaries. The device shows good response to UV light and a very low response to visible light. The dark current is less than 10 pA. The device response time is less than 20 μs. Furthermore, the device reveals little change in spectral response with increasing temperature at all wavelengths. © 2002 Elsevier Science B.V. All rights reserved.