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Directly deposited optical-blocking filters for single-photon x-ray imaging spectroscopy

June 28, 2017
  |
Journal Article
Author:
Kevin K. Ryu
…
Published in:
J. Astron. Telesc. Instrum. Syst., Vol. 3, No. 3 (2017), 036001.
Topic:
photonics
R&D area:
R&D group:

Summary

Directly deposited optical-blocking filters (DD OBFs) have the potential to improve filter performance and lower risk and cost for future x-ray imaging spectroscopy missions. However, they have not been fully characterized on high-performance charge coupled devices (CCDs). This paper reports the results of DD OBFs processed on high-performance photon-counting CCDs. It is found that CCD performance is not degraded by deposition of such filters. X-ray and optical transmission through the OBF is characterized and found to match theoretical expectation. Light-leaks through pinholes and the side and back surfaces are found to lower the optical extinction ratio; various coating processes are developed to resolve these issues.
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Summary

Directly deposited optical-blocking filters (DD OBFs) have the potential to improve filter performance and lower risk and cost for future x-ray imaging spectroscopy missions. However, they have not been fully characterized on high-performance charge coupled devices (CCDs). This paper reports the results of DD OBFs processed on high-performance photon-counting CCDs...

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Directly deposited optical-blocking filters for single-photon x-ray imaging spectroscopy

Directly-deposited blocking filters for high-performance silicon x-ray detectors

July 1, 2016
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Conference Paper
Author:
Marshall W. Bautz
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Published in:
SPIE, Vol. 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, July 2016, 99054C.
Topic:
detection systems
R&D area:
R&D group:

Summary

Silicon X-ray detectors often require blocking filters to mitigate noise and out-of-band signal from UV and visible backgrounds. Such filters must be thin to minimize X-ray absorption, so direct deposition of filter material on the detector entrance surface is an attractive approach to fabrication of robust filters. On the other hand, the soft (E < 1 keV) X-ray spectral resolution of the detector is sensitive to the charge collection efficiency in the immediate vicinity of its entrance surface, so it is important that any filter layer is deposited without disturbing the electric field distribution there. We have successfully deposited aluminum blocking filters, ranging in thickness from 70 to 220nm, on back-illuminated CCD X-ray detectors passivated by means of molecular beam epitaxy. Here we report measurements showing that directly deposited filters have little or no effect on soft X-ray spectral resolution. We also find that in applications requiring very large optical density (> OD 6) care must be taken to prevent light from entering the sides and mounting surfaces of the detector. Our methods have been used to deposit filters on the detectors of the REXIS instrument scheduled to fly on OSIRIS-ReX later this year.
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Summary

Silicon X-ray detectors often require blocking filters to mitigate noise and out-of-band signal from UV and visible backgrounds. Such filters must be thin to minimize X-ray absorption, so direct deposition of filter material on the detector entrance surface is an attractive approach to fabrication of robust filters. On the other...

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Directly-deposited blocking filters for high-performance silicon x-ray detectors

Development of CCDs for REXIS on OSIRIS-REx

July 24, 2014
  |
Conference Paper
Author:
Kevin K. Ryu
…
Published in:
SPIE, Vol. 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 22 June 2014, 91444O.
Topic:
optics
R&D area:
R&D group:

Summary

The Regolith x-ray Imaging Spectrometer (REXIS) is a coded-aperture soft x-ray imaging instrument on the OSIRIS-REx spacecraft to be launched in 2016. The spacecraft will fly to and orbit the near-Earth asteroid Bennu, while REXIS maps the elemental distribution on the asteroid using x-ray fluorescence. The detector consists of a 2x2 array of back-illuminated 1kX1k frame transfer CCDs with a flight heritage to Suzaku and Chandra. The back surface has a thing p+-doped layer deposited by molecular-beam epitaxy (MBE) for maximum quantum efficiency and energy resolution at low x-ray energies. The CCDs also feature an integrated optical-blocking filter (OBF) to suppress visible and near-infrared light. The OBF is an aluminum film deposited directly on the CCD back surface and is mechanically more robust and less absorptive of x-rays than the conventional free-standing aluminum-coated polymer films. The CCDs have charge transfer inefficiencies of less than 10^-6, and dark current of le-/pixel/second at the REXIS operating temperature of -60 degrees C. The resulting spectral resolution is 115 eV at 2 KeV. The extinction ratio of the filter is ~10^12 at 625 nm.
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Summary

The Regolith x-ray Imaging Spectrometer (REXIS) is a coded-aperture soft x-ray imaging instrument on the OSIRIS-REx spacecraft to be launched in 2016. The spacecraft will fly to and orbit the near-Earth asteroid Bennu, while REXIS maps the elemental distribution on the asteroid using x-ray fluorescence. The detector consists of a...

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Development of CCDs for REXIS on OSIRIS-REx

Back-illuminated three-dimensionally integrated CMOS image sensors for scientific applications

August 27, 2007
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Conference Paper
Author:
Vyshnavi Suntharalingam
…
Published in:
SPIE Vol. 6690, Focal Plane Arrays for Space Telescopes III, 27-28 August 2007, 669009.
Topic:
sensors
R&D area:
R&D group:

Summary

SOI-based active pixel image sensors have been built in both monolithic and vertically interconnected pixel technologies. The latter easily supports the inclusion of more complex pixel circuitry without compromising pixel fill factor. A wafer-scale back-illumination process is used to achieve 100% fill factor photodiodes. Results from 256 x 256 and 1024 x 1024 pixel arrays are presented, with discussion of dark current improvement in the differing technologies.
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Summary

SOI-based active pixel image sensors have been built in both monolithic and vertically interconnected pixel technologies. The latter easily supports the inclusion of more complex pixel circuitry without compromising pixel fill factor. A wafer-scale back-illumination process is used to achieve 100% fill factor photodiodes. Results from 256 x 256 and...

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Back-illuminated three-dimensionally integrated CMOS image sensors for scientific applications

Soft-x-ray CCD imagers for AXAF

October 1, 1997
  |
Journal Article
Author:
Barry E. Burke
…
Published in:
IEEE Trans. Electron Devices, Vol. 44, No. 10, October 1997, pp. 1633-1642.
Topic:
sensors
R&D area:
R&D group:

Summary

We describe the key features and performance data of a 1024 x 1026-pixel frame-transfer imager for use as a soft-x-ray detector on the NASA X-ray observatory Advanced X-ray Astrophysics Facility (AXAF). The four-port device features a floating-diffusion output circuit with a responsivity of 20/spl mu/V/e/sup -/ and noise of about 2 e/sup -/ at a 100-kHz data rate. Techniques for achieving the low sense-node capacitance of 5 fF are described. The CCD is fabricated on high-resistivity p-type silicon for deep depletion and includes narrow potential troughs for transfer inefficiencies of around 10/sup -7/ (ten to the negative 7). To achieve good sensitivity at energies below 1 keV, we have developed a back-illumination process that features low recombination losses at the back surface and has produced efficiencies of about 0.7 at 277 eV (carbon K/spl alpha/).
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Summary

We describe the key features and performance data of a 1024 x 1026-pixel frame-transfer imager for use as a soft-x-ray detector on the NASA X-ray observatory Advanced X-ray Astrophysics Facility (AXAF). The four-port device features a floating-diffusion output circuit with a responsivity of 20/spl mu/V/e/sup -/ and noise of about...

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Soft-x-ray CCD imagers for AXAF
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