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27 August 1999 Thin film photodetectors for the UV and vacuum UV spectral range
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We present the first semiconductor p-i-n photodiode with excellent sensitivity in the VUV range and high rejection of visible radiation. The device is based on the thin-film technology of amorphous silicon and silicon carbide and can be integrated in large area arrays on glass or flexible substrate. Its internal quantum efficiency is over 50 percent in the VUV and decreases with wavelength. In the visible range the sensitivity can be tuned by variations to the technology parameters. Solar blind photodiodes have been fabricated, with 1 percent quantum efficiency at 400 nm and 0.1 at 650 nm. Working bias voltage is very low since its best sensitivity is achieved when reversely biased with 0.3V. Linearity of the photocurrent was verified with incident UV light in the range 5nW to 4mW. Response times under UV illumination was tested with a N2 laser: 500 ns rise times and 6microsecond(s) FWHM were measured. The excellent behavior of the photodetector in the UV range was explained in the UV range was explained within the hypotheses that generation of hot carriers in the p-doped layer occurs and that a pure diffusion mechanism rules transport, being the thickness of the p-doped layer comparable with the effective diffusion length of electrons.
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Giampiero de Cesare, Fernanda Irrera, and Piergiorgio Nicolosi "Thin film photodetectors for the UV and vacuum UV spectral range", Proc. SPIE 3737, Design and Engineering of Optical Systems II, (27 August 1999);

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