Title: The effects of large signals on charge collection in radiation detectors: Application to amorphous selenium detectors
Authors: Kabir, MZ ×
Emelianova, Evguenia
Arkhipov, VI
Yunus, M
Kasap, SO
Adriaenssens, Guy #
Issue Date: Jun-2006
Publisher: American Institute of Physics
Series Title: Journal of Applied Physics vol:99 issue:12 pages:1-8
Article number: 124501
Abstract: Analytical and numerical models for studying the effects of large signals on charge collection efficiency in radiation detectors are described by considering bimolecular recombination between drifting charge carriers, carrier trapping, and space charge effects. First, an analytical solution is obtained by assuming that the field remains relatively uniform. Then the continuity equations for both holes and electrons, and Poisson's equation across the photoconductor for a short pulse irradiation are simultaneously solved by the finite difference method, without any assumptions. There is a very good agreement between the approximate analytical and numerical solutions for the charge collection efficiency. The numerical results are also compared with Monte Carlo simulations of carrier transport. The charge collection efficiency model is applied to amorphous selenium x-ray image detectors. The bimolecular-recombination-limited charge collection efficiency depends on the total photogenerated carrier density rather than on its spatial distribution. It is found that the recombination plays practically no role up to the total instantaneous carrier generation Q(0) of 10(9) EHPs/cm(2) at the applied electric field of 10 V/mu m. The effect of recombination on charge collection increases with decreasing applied electric field strength. For high carrier generation (e.g., Q(0) of 10(12) EHPs/cm(2) for an applied field of 10 V/mu m), the electric field distributions vary widely across the photoconductor thickness during the travel of charge carriers towards the electrodes. However, the effect of bimolecular recombination on charge collection efficiency is almost independent of bias polarity and the field distribution. The numerical results are also compared with recent experimental data available in the literature.
ISSN: 0021-8979
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Semiconductor Physics Section
× corresponding author
# (joint) last author

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