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Proceedings Paper

DC and AC performance of leaky-mode metal-semiconductor-metal polysilicon photodetectors
Author(s): Robert Pownall; Guangwei Yuan; Charles Thangaraj; Joel Kindt; Tom W. Chen; Phil Nikkel; Kevin L. Lear
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Paper Abstract

Metal-semiconductor-metal (MSM) polysilicon photodetectors which are compatible with all standard complementary metal-oxide-semiconductor (CMOS) processes and which were made in a commercial 0.35 ìm process have demonstrated DC responsivities up to 1.3 A/W at 690 nm. An effective absorption coefficient of 0.63 dB/ìm was found from a comparison of responsivities of 5- and 10-μm long detectors. For a constant bias voltage, responsivity varies as the inverse square of the contact spacing, with responsivity continuing to increase for the smallest available contact spacing devices. Responsivities corresponding to quantum efficiencies over 200% were observed, implying a gain mechanism. For AC performance, electrical pulse full-width at half-maximum (FWHM) as low as 0.81 ns and 10% - 90% rise times as low as 0.39 ns have been measured in response to ~0.65 ns FWHM optical input pulses. The ability to modulate the source laser diode limits the measured pulse performance of the detectors. Observed DC and pulse results are well explained by an analytic expression which incorporates the effects of bulk and contact recombination. Possible means of improving the detector speed are proposed.2

Paper Details

Date Published: 25 February 2010
PDF: 12 pages
Proc. SPIE 7598, Optical Components and Materials VII, 759811 (25 February 2010); doi: 10.1117/12.843002
Show Author Affiliations
Robert Pownall, Colorado State Univ. (United States)
Guangwei Yuan, Avago Technologies Ltd. (United States)
Charles Thangaraj, Colorado State Univ. (United States)
Joel Kindt, Colorado State Univ. (United States)
Tom W. Chen, Colorado State Univ. (United States)
Phil Nikkel, Avago Technologies Ltd. (United States)
Kevin L. Lear, Colorado State Univ. (United States)

Published in SPIE Proceedings Vol. 7598:
Optical Components and Materials VII
Shibin Jiang; Michel J. F. Digonnet; John W. Glesener; J. Christopher Dries, Editor(s)

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