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Proceedings Paper

Integrated x-ray and charged particle active pixel CMOS sensor arrays using an epitaxial silicon-sensitive region
Author(s): Stuart Kleinfelder; Hans Bichsel; Fred Bieser; Howard S. Matis; Gulshan Rai; Fabrice Retiere; Howard Wieman; Eugene Yamamoto
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Paper Abstract

Integrated CMOS Active Pixel Sensor (APS) arrays have been fabricated and tested using X-ray and electron sources. The 128 by 128 pixel arrays, designed in a standard 0.25 micron process, use a ~10 micron epitaxial silicon layer as a deep detection region. The epitaxial layer has a much greater thickness than the surface features used by standard CMOS APS, leading to stronger signals and potentially better signal-to-noise ratio (SNR). On the other hand, minority carriers confined within the epitaxial region may diffuse to neighboring pixels, blur images and reduce peak signal intensity. But for low-rate, sparse-event images, centroid analysis of this diffusion may be used to increase position resolution. Careful trade-offs involving pixel size and sense-node area verses capacitance must be made to optimize overall performance. The prototype sensor arrays, therefore, include a range of different pixel designs, including different APS circuits and a range of different epitaxial layer contact structures. The fabricated arrays were tested with 1.5 GeV electrons and Fe-55 X-ray sources, yielding a measured noise of 13 electrons RMS and an SNR for single Fe-55 X-rays of greater than 38.

Paper Details

Date Published: 10 January 2003
PDF: 10 pages
Proc. SPIE 4784, X-Ray and Gamma-Ray Detectors and Applications IV, (10 January 2003); doi: 10.1117/12.450826
Show Author Affiliations
Stuart Kleinfelder, Univ. of California/Irvine (United States)
Hans Bichsel, University of Washington (United States)
Fred Bieser, Lawrence Berkeley National Lab. (United States)
Howard S. Matis, Lawrence Berkeley National Lab. (United States)
Gulshan Rai, Lawrence Berkeley National Lab. (United States)
Fabrice Retiere, Lawrence Berkeley National Lab. (United States)
Howard Wieman, Lawrence Berkeley National Lab. (United States)
Eugene Yamamoto, Lawrence Berkeley National Lab. (United States)


Published in SPIE Proceedings Vol. 4784:
X-Ray and Gamma-Ray Detectors and Applications IV
Ralph B. James; Larry A. Franks; Arnold Burger; Edwin M. Westbrook; Roger D. Durst; Edwin M. Westbrook; Roger D. Durst, Editor(s)

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