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Proceedings Paper

Modelling and testing the x-ray performance of CCD and CMOS APS detectors using numerical finite element simulations
Author(s): Daniel P. Weatherill; Konstantin D. Stefanov; Thomas A. Greig; Andrew D. Holland
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Paper Abstract

Pixellated monolithic silicon detectors operated in a photon-counting regime are useful in spectroscopic imaging applications. Since a high energy incident photon may produce many excess free carriers upon absorption, both energy and spatial information can be recovered by resolving each interaction event. The performance of these devices in terms of both the energy and spatial resolution is in large part determined by the amount of diffusion which occurs during the collection of the charge cloud by the pixels. Past efforts to predict the X-ray performance of imaging sensors have used either analytical solutions to the diffusion equation or simplified monte carlo electron transport models. These methods are computationally attractive and highly useful but may be complemented using more physically detailed models based on TCAD simulations of the devices. Here we present initial results from a model which employs a full transient numerical solution of the classical semiconductor equations to model charge collection in device pixels under stimulation from initially Gaussian photogenerated charge clouds, using commercial TCAD software. Realistic device geometries and doping are included. By mapping the pixel response to different initial interaction positions and charge cloud sizes, the charge splitting behaviour of the model sensor under various illuminations and operating conditions is investigated. Experimental validation of the model is presented from an e2v CCD30-11 device under varying substrate bias, illuminated using an Fe-55 source.

Paper Details

Date Published: 23 July 2014
PDF: 10 pages
Proc. SPIE 9154, High Energy, Optical, and Infrared Detectors for Astronomy VI, 91541A (23 July 2014); doi: 10.1117/12.2056302
Show Author Affiliations
Daniel P. Weatherill, The Open Univ. (United Kingdom)
Konstantin D. Stefanov, The Open Univ. (United Kingdom)
Thomas A. Greig, e2v technologies plc (United Kingdom)
Andrew D. Holland, The Open Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 9154:
High Energy, Optical, and Infrared Detectors for Astronomy VI
Andrew D. Holland; James Beletic, Editor(s)

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