Dissertation/Thesis Abstract

Hybrid CMOS SiPIN detectors as astronomical imagers
by Simms, Lance Michael, Ph.D., Stanford University, 2010, 247; 3395872
Abstract (Summary)

Charge Coupled Devices (CCDs) have dominated optical and x-ray astronomy since their inception in 1969. Only recently, through improvements in design and fabrication methods, have imagers that use Complimentary Metal Oxide Semiconductor (CMOS) technology gained ground on CCDs in scientific imaging. We are now in the midst of an era where astronomers might begin to design optical telescope cameras that employ CMOS imagers. The first three chapters of this dissertation are primarily composed of introductory material. In them, we discuss the potential advantages that CMOS imagers offer over CCDs in astronomical applications. We compare the two technologies in terms of the standard metrics used to evaluate and compare scientific imagers: dark current, read noise, linearity, etc. We also discuss novel features of CMOS devices and the benefits they offer to astronomy. In particular, we focus on a specific kind of hybrid CMOS sensor that uses Silicon PIN photodiodes to detect optical light in order to overcome deficiencies of commercial CMOS sensors.

The remaining four chapters focus on a specific type of hybrid CMOS Silicon PIN sensor: the Teledyne Hybrid Visible Silicon PIN Imager (HyViSI). In chapters four and five, results from testing HyViSI detectors in the laboratory and at the Kitt Peak 2.1m telescope are presented. We present our laboratory measurements of the standard detector metrics for a number of HyViSI devices, ranging from 1k×1k to 4k×4k format. We also include a description of the SIDECAR readout circuit that was used to control the detectors. We then show how they performed at the telescope in terms of photometry, astrometry, variability measurement, and telescope focusing and guiding.

Lastly, in the final two chapters we present results on detector artifacts such as pixel crosstalk, electronic crosstalk, and image persistence. One form of pixel crosstalk that has not been discussed elsewhere in the literature, which we refer to as Interpixel Charge Transfer (IPCT), is introduced. This effect has an extremely significant impact on x-ray astronomy. For persistence, a new theory and accompanying simulations are presented to explain latent images in the HyViSI.

In consideration of these artifacts and the overall measured performance, we argue that HyViSI sensors are ready for application in certain regimes of astronomy, such as telescope guiding, measurements of fast planetary transits, and x-ray imaging, but not for others, such as deep field imaging and large focal plane astronomical surveys.

Indexing (document details)
Advisor: Kahn, Steven M.
School: Stanford University
School Location: United States -- California
Source: DAI-B 71/01, Dissertation Abstracts International
Subjects: Electrical engineering, Astronomy
Keywords: Astronomical imagers, CMOS imagers, Pixel crosstalk, Silicon photodiodes
Publication Number: 3395872
ISBN: 978-1-109-58363-2
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