Hall, DJ;
Wood, D;
Murray, NJ;
Gow, JPD;
Chroneos, A;
Holland, A;
(2017)
In situ trap properties in CCDs: The donor level of the silicon divacancy.
Journal of Instrumentation
, 12
, Article P01025. 10.1088/1748-0221/12/01/P01025.
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Abstract
The silicon divacancy is one of the main defects of concern in radiation damage studies of Charge-Coupled Devices (CCDs) and, being immobile at room temperature, the defect is accessible to a variety of characterisation techniques. As such, there is a large amount of (often conflicting) information in the literature regarding this defect. Here we study the donor level of the divacancy, one of three energy levels which lie between the silicon valence and conduction bands. The donor level of the divacancy acts as a trap for holes in silicon and therefore can be studied through the use of a p-channel CCD. The method of trap-pumping, linked closely to the process of pocket-pumping, has been demonstrated in the literature over the last two years to allow for in-situ analysis of defects in the silicon of CCDs. However, most work so far has been a demonstartion of the techinique. We begin here to use the technique for detailed studies of a specific defect centre in silicon, the donor level of the divacancy. The trap density post-irradiation can be found, and each instance of the trap identified independently of all others. Through the study of the trap response at different clocking frequencies one can measure directly the defect emission time constant, and through tracking this at different temperatures, it is possible to use Shockley-Read-Hall theory to calculate the trap energy level and cross-section. A large population of traps, all with parameters consistent with the donor level of the divacancy, has been studied, leading to a measure of the distribution of properties. The emission time constant, energy level and cross-section are found to have relatively large spreads, significantly beyond the small uncertainty in the measurement technique. This spread has major implications on the correction of charge transfer inefficiency effects in space applications in which high precision is required.
Type: | Article |
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Title: | In situ trap properties in CCDs: The donor level of the silicon divacancy |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1088/1748-0221/12/01/P01025 |
Publisher version: | http://doi.org/10.1088/1748-0221/12/01/P01025 |
Language: | English |
Additional information: | Copyright © 2017 IOP Publishing Ltd and Sissa Medialab srl. All rights reserved. This is an author-created, un-copyedited version of an article accepted for publication/published in Journal of Instrumentation IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at 10.1088/1748-0221/12/01/P01025 |
Keywords: | Divacancy, CCD, defect, trap, pocket-pumping, trap-pumping, radiation damage, p-channel |
UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1545182 |
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