GaAs structures for X-ray imaging detectors

Ayzenshtat, G. I.; Bakin, N. N.; Budnitsky, D.L.; Drugova, E. P.; Germogenov, V. P.; Khludkov, S. S.; Koretskaya, O. B.; Okaevich, L.S.; Porokhovnichenko, L. P.; Потапов, А. И.; Smith, K. M.; Толбанов, О. П.; Tyazhev, A.; Vilisova, M. D.; Vorobiev, A.P.

doi:10.1016/s0168-9002(01)00820-8

Cited by 24 publications

(21 citation statements)

References 9 publications

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“…The high resistivity GaAs material used in this study was produced at the Tomsk State University by the high temperature diffusion of Cr into n-type melt-grown wafers [22]. This technique previously demonstrated to provide sensors with resistivities in the order of cm [23], [28], [29] via high compensation rates.…”

Section: Detector Fabrication and Chip Descriptionmentioning

confidence: 99%

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Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor

Hamann

Koenig

Zubér

et al. 2015

IEEE Trans. Med. Imaging

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High resistivity gallium arsenide is considered a suitable sensor material for spectroscopic X-ray imaging detectors. These sensors typically have thicknesses between a few hundred μm and 1 mm to ensure a high photon detection efficiency. However, for small pixel sizes down to several tens of μm, an effect called charge sharing reduces a detector's spectroscopic performance. The recently developed Medipix3RX readout chip overcomes this limitation by implementing a charge summing circuit, which allows the reconstruction of the full energy information of a photon interaction in a single pixel. In this work, we present the characterization of the first Medipix3RX detector assembly with a 500 μm thick high resistivity, chromium compensated gallium arsenide sensor. We analyze its properties and demonstrate the functionality of the charge summing mode by means of energy response functions recorded at a synchrotron. Furthermore, the imaging properties of the detector, in terms of its modulation transfer functions and signal-to-noise ratios, are investigated. After more than one decade of attempts to establish gallium arsenide as a sensor material for photon counting detectors, our results represent a breakthrough in obtaining detector-grade material. The sensor we introduce is therefore suitable for high resolution X-ray imaging applications.

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Section: Detector Fabrication and Chip Descriptionmentioning

confidence: 99%

“…However, in the past decade, an alternative approach of producing GaAs sensors was introduced to overcome these problems [22]. It is based on the compensation of GaAs wafers by chromium (Cr) diffusion and has shown to provide fully active, high resistivity (HR) sensors with thicknesses up to 1 mm [21].…”

Section: Introductionmentioning

confidence: 99%

Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor

Hamann

Koenig

Zubér

et al. 2015

IEEE Trans. Med. Imaging

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“…al. in 2001, where standard n-type GaAs wafers are doped with Cr by diffusion [4]. The Cr compensates the excess electrons in this material, thus achieving high enough resistivity to allow it to be used as a photoconductor detector with ohmic contacts.…”

Section: Chromium-compensated Gallium Arsenidementioning

confidence: 99%

The LAMBDA photon-counting pixel detector and high-Z sensor development

et al. 2014

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Many X-ray experiments at third-generation synchrotrons benefit from using singlephoton-counting detectors, due to their high signal-to-noise ratio and potential for high-speed measurements. LAMBDA (Large Area Medipix3-Based Detector Array) is a pixel detector system based on the Medipix3 readout chip. It combines the features of Medipix3, such as a small pixel size of 55 µm and flexible functionality, with a large tileable module design consisting of 12 chips (1536 × 512 pixels) and a high-speed readout system capable of running at 2000 frames per second.To enable high-speed experiments with hard X-rays, the LAMBDA system has been combined with different high-Z sensor materials. Room-temperature systems using GaAs and CdTe systems have been produced and tested with X-ray tubes and at synchrotron beamlines. Both detector materials show nonuniformities in their raw image response, but the pixel yield is high and the uniformity can be improved by flat-field correction, particularly in the case of GaAs. High-frame-rate experiments show that useful information can be gained on millisecond timescales in synchrotron experiments with these sensors.

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“…The thermal conditions employed do not allow one to produce bulk i-GaAs with an EL2 density less than 10 15 cm -3 [24].…”

Section: Selection Of a Sensing Materialsmentioning

confidence: 99%

GaAs Pixel-Detector Technology for X-ray Medical Imaging: A Review

2005

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An attempt is made to analyze and summarize the literature data on hybrid x-ray GaAs pixel detectors designed for medical imaging. Criteria are stated for selecting a semiconductor material. It is shown that GaAs is currently preferable to the other semiconductor materials. Detector figures of merit used to select a semiconductor material and a process technology are listed. Major types of x-ray detector based on bulk-grown or epitaxial GaAs are described, namely, the planar Schottky, the planar p-i-n, and the 3D detector. The influence is considered of different process steps (contact formation, passivation coating, hybridization, etc.) on detector figures of merit. Monolithic technology is briefly discussed.

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GaAs structures for X-ray imaging detectors

Cited by 24 publications

References 9 publications

Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor

Performance of a Medipix3RX Spectroscopic Pixel Detector With a High Resistivity Gallium Arsenide Sensor

The LAMBDA photon-counting pixel detector and high-Z sensor development

GaAs Pixel-Detector Technology for X-ray Medical Imaging: A Review

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