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Germanium CCDs for large-format SWIR and x-ray imaging

Summary

Germanium exhibits high sensitivity to short-wave infrared (SWIR) and X-ray radiation, making it an interesting candidate for imaging applications in these bands. Recent advances in germanium processing allow for high-quality charge-coupled devices (CCDs) to be realized in this material. In this article, we discuss our evaluation of germanium as an absorber material for CCDs via fabrication and analysis of discrete devices such as diodes, metal-insulator-semiconductor capacitors, and buried-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). We then describe fabrication of our first imaging device on germanium, a 32 x 1 x 8.1 um linear shift register. Based on this work, we find that germanium is a promising material for CCDs imaging in the SWIR and X-ray bands.
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Summary

Germanium exhibits high sensitivity to short-wave infrared (SWIR) and X-ray radiation, making it an interesting candidate for imaging applications in these bands. Recent advances in germanium processing allow for high-quality charge-coupled devices (CCDs) to be realized in this material. In this article, we discuss our evaluation of germanium as an...

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A study of crosstalk in a 256 x 256 photon counting imager based on silicon Geiger-mode avalanche photodiodes

Published in:
IEEE Sens. J., Vol. 15, No. 4, April 2015, pp. 2123-32.

Summary

We demonstrate a 256 x 256 passive photon counting imager based on hybridization of back-illuminated silicon Geiger-mode avalanche photodiodes to an all-digital CMOS counting chip. Photon detection efficiencies in the 10%-20% are observed at visible wavelengths. The detection efficiency is currently limited by optical crosstalk that leads to elevation of dark count rates as the bias voltage on the photodiodes is increased. Both the time dependence of dark count activity during a gate time and the spatial structure of dark images were successfully explained using crosstalk-based models.
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Summary

We demonstrate a 256 x 256 passive photon counting imager based on hybridization of back-illuminated silicon Geiger-mode avalanche photodiodes to an all-digital CMOS counting chip. Photon detection efficiencies in the 10%-20% are observed at visible wavelengths. The detection efficiency is currently limited by optical crosstalk that leads to elevation of...

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Geiger-mode quad-cell array for adaptive optics

Published in:
CLEO-QELS, 2008 Conf. on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conf., 4-9 May 2008.

Summary

We report an array of Shack-Hartmann wavefront sensors using high-fill-factor Geiger-mode avalanche detector quad cells hybridized to all-digital CMOS counting circuits. The absence of readout noise facilitates fast wavefront sensing at low light levels.
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Summary

We report an array of Shack-Hartmann wavefront sensors using high-fill-factor Geiger-mode avalanche detector quad cells hybridized to all-digital CMOS counting circuits. The absence of readout noise facilitates fast wavefront sensing at low light levels.

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Laser radar imager based on 3D integration of Geiger-mode avalanche photodiodes with two SOI timing circuit layers

Summary

We have developed focal-plane arrays and laser-radar (ladar) imaging systems based on Geiger-mode avalanche photodiodes (APDs) integrated with high-speed all-digital CMOS timing circuits. A Geiger-mode APD produces a digital pulse upon detection of a single photon. This pulse is used to stop a fast digital counter in the pixel circuit, thereby measuring photon arrival time. This "photon-to-digital conversion" yields quantum-limited sensitivity and noiseless readout, enabling high-performance ladar systems. Previously reported focal planes, based on bump bonding or epoxy bonding the APDs to foundry chips, had coarse (100um) pixel spacing and 0.5ns timing quantization.
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Summary

We have developed focal-plane arrays and laser-radar (ladar) imaging systems based on Geiger-mode avalanche photodiodes (APDs) integrated with high-speed all-digital CMOS timing circuits. A Geiger-mode APD produces a digital pulse upon detection of a single photon. This pulse is used to stop a fast digital counter in the pixel circuit...

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Geiger-mode avalanche photodiodes for three-dimensional imaging

Published in:
Lincoln Laboratory Journal, Vol. 13, No. 2, 2002, pp. 335-350.

Summary

We discuss the properties of Geiger-mode avalanche photodiodes (APDs) and their use in developing an imaging laser radar (ladar). This type of photodetector gives a fast electrical pulse in response to the detection of even a single photon, allowing for sub-nsec-precision photon-flight-time measurement. We present ongoing work at Lincoln Laboratory on three-dimensional (3D) imaging with arrays of these diodes, and the integration of the arrays with fast complementary metal-oxide semiconductor (CMOS) digital timing circuits.
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Summary

We discuss the properties of Geiger-mode avalanche photodiodes (APDs) and their use in developing an imaging laser radar (ladar). This type of photodetector gives a fast electrical pulse in response to the detection of even a single photon, allowing for sub-nsec-precision photon-flight-time measurement. We present ongoing work at Lincoln Laboratory...

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