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Proceedings Paper

Ultraviolet sensitivity of a teledyne-e2v EMCCD
Author(s): Neil Rowlands; Ken Smith; Olivier Daigle; Oleg Djazovski; Alan Scott; Alexander Beaton; Andrew Wilson
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Paper Abstract

Electron multiplying charged coupled devices (EMCCD’s) can provide significantly greater signal to noise ratios in low light conditions and/or for higher speed readout than traditional CCDs. Due to the electron multiplication before readout, the effective readout noise can be at the sub-electron level, enabling single photon counting. Traditional far UV (150 – 200 nm) imaging detectors have utilized micro-channel plates to detect usually scarce UV photons at low efficiency, amplify them into electron showers which strike a phosphor, allowing a silicon detector array to perform the final detection of the resulting visible light pulse. The typical efficiencies of UV photo detection with MCP systems ranges from a low of a few percent to as high as 25%. Given that the theoretical probability of absorption of UV photons in silicon is at least 30% in this wavelength range, then it should be possible to make use of a photon counting EMCCD to directly detect UV photons that is competitive with MCP performance. We approached Teledyne-e2v and they confirmed that a backside thinned EMCCD with their ‘astro no-coat’ process should provide reasonable quantum efficiency (ie. > 30%) in this range. The primary application in which we are interested is UV imaging of the aurora from space-based platforms. In this application there are system level advantages to replacing an MCP based detector with an EMCCD which is directly sensitive to UV illumination, namely the elimination of a high voltage power supply and higher spatial resolution. An MCP produces an electron shower which degrades image quality and also requires a relatively thick detector window which has to be accommodated in the imager optical design. We acquired five CCD201 engineering model EMCCDs with e2v’s ‘astro no-coat’ process, and incorporated one of these into a standard flexible liquid nitrogen cooled EMCCD camera produced by Nüvü Camēras. Once installed the EMCCD operation was confirmed with standard Nüvü Camēras test procedures. The camera was then mounted in a test vacuum chamber along with a McPherson UV monochromator so that the UV performance could be assessed. A NIST traceable photodiode was used for the absolute calibration. The resulting intrinsic QE was found to be 34% at 180 nm rising to 44% at 150 nm. The quantum yield was found to be quite low, only a few percent at 180 nm rising to only 1.13-1.18 at 150 nm. This is considerably lower than comparable results from CCDs where delta-doping has been used to improve the responsive quantum efficiency and also lower than a Teledyne-e2v CMOS sensor with the same surface treatment.

Paper Details

Date Published: 20 July 2018
PDF: 20 pages
Proc. SPIE 10709, High Energy, Optical, and Infrared Detectors for Astronomy VIII, 107090D (20 July 2018); doi: 10.1117/12.2313022
Show Author Affiliations
Neil Rowlands, Honeywell Aerospace (Canada)
Ken Smith, Honeywell Aerospace (Canada)
Olivier Daigle, Nüvü Camēras Inc. (Canada)
Oleg Djazovski, Canadian Space Agency (Canada)
Alan Scott, Honeywell Aerospace (Canada)
Alexander Beaton, Honeywell Aerospace (Canada)
Andrew Wilson, Honeywell Aerospace (Canada)

Published in SPIE Proceedings Vol. 10709:
High Energy, Optical, and Infrared Detectors for Astronomy VIII
Andrew D. Holland; James Beletic, Editor(s)

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