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Proceedings Paper

A megapixel class HgCdTe linear mode avalanche photo-diode array for low background astronomy (Conference Presentation)
Author(s): Donald N. B. Hall; Ian M. Baker; Vincent Isgar; Shane M. Jacobson; Harald Weller

Paper Abstract

With gain-normalized dark currents reduced below 10 e-/s/pixel, HgCdTe Avalanche Photo-Diode arrays operated in linear mode are now widely accepted as the sensors of choice for adaptive optics wavefront sensing of natural guide stars in the wavelength range 1 to 2.5 um. At lower temperatures the intrinsic dark currents in Leonardo’s SAPHIRA 320 x 256 @ 24um pitch arrays have recently been shown to be four orders of magnitude lower, approaching 0.001 e-/s/pixel. This has opened the way to megapixel class APD arrays offering major advantages for a wide range of low background astronomical observations. We report the status of development of a 1k x 1k @ 15um pixel Read-Out Integrated Circuit (ROIC) for a three-side close-buttable, 16 output, MOVPE HgCdTe array with reference pixels and reference outputs. The design has been optimized for minimum ROIC glow following a detailed investigation of glow sources in the SAPHIRA ME1001 ROIC. This involved precisely overlaying J-band glow images on layout drawings from EDA software to identify all the sources of glow. As of the time of submission of this abstract, the Architecture definition is in its third iteration and the program is on track to produce ROICs around mid-2018. In parallel, Mark 20 SAPHIRAs optimized for very low background operation with the goal of delaying the onset of tunnel-tunnel current to bias voltages producing useful avalanche gain are being characterized along with modified SAPHIRAs with 15um pixels.

Paper Details

Date Published: 10 July 2018
Proc. SPIE 10709, High Energy, Optical, and Infrared Detectors for Astronomy VIII, 107091N (10 July 2018); doi: 10.1117/12.2314897
Show Author Affiliations
Donald N. B. Hall, Institute for Astronomy (United States)
Ian M. Baker, Leonardo MW Ltd. (United Kingdom)
Vincent Isgar, Leonardo MW Ltd. (United Kingdom)
Shane M. Jacobson, Institute for Astronomy (United States)
Harald Weller, Leonardo MW Ltd. (United Kingdom)

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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