GaAs Pixel Detectors

Tyazhev, A.; Budnitsky, D.L.; Mokeev, D.Y.; Новиков, В. А.; Zarubin, A.; Толбанов, О. П.; Shelkov, G.A.; Hamann, Elias; Fauler, A.; Fiederle, M.; Procz, S.

doi:10.1557/opl.2013.1144

Cited by 7 publications

(7 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The chromium compensated GaAs material used in this study was produced by Tomsk State University (TSU) in Russia [19,20]. It was used to fabricate sensor devices with 128 × 128 1A sensor thickness of 500 µm is common for GaAs sensors.…”

Section: Gaas:cr Sensor Materialsmentioning

confidence: 99%

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

et al. 2018

View full text Add to dashboard Cite

A: We studied the properties of chromium compensated GaAs when coupled to charge integrating ASICs as a function of detector temperature, applied bias and x-ray tube energy. The material is a photoresistor and can be biased to collect either electrons or holes by the pixel circuitry. Both are studied here. Previous studies have shown substantial hole trapping. This trapping and other sensor properties give rise to several non-ideal effects which include an extended point spread function, variations in the effective pixel size, and rate dependent offset shifts. The magnitude of these effects varies with temperature and bias, mandating good temperature uniformity in the sensor and very good temperature stabilization, as well as a carefully selected bias voltage.

show abstract

Section: Gaas:cr Sensor Materialsmentioning

confidence: 99%

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

et al. 2018

View full text Add to dashboard Cite

show abstract

“…This technique previously demonstrated to provide sensors with resistivities in the order of cm [23], [28], [29] via high compensation rates. Due to the high dopant concentration, the width of the space charge regions (SCR) behind the metal (Schottky) contacts are small, leading to the bias voltage dropping mainly across the sensor and thus to a uniform distribution of the electric field [21], [24], [30]. This implies that the whole sensor volume is sensitive to radiation, and dead layers, which were sometimes reported to be present in epitaxial [31] and low-resistivity (EL2-compensated) bulk material with Schottky contacts [20], are absent.…”

Section: Detector Fabrication and Chip Descriptionmentioning

confidence: 99%

“…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]. As was demonstrated recently [23], [24], these HR-GaAs:Cr sensors exhibit detector-grade material properties and, in combination with photon counting Timepix readout chips, provide an excellent image quality.…”

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

View full text Add to dashboard Cite

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.

show abstract

“…Gallium arsenide (GaAs) has been regarded as promising for X-and gamma ray detection since more than half a century now [7], but never had sustained success due to limited active layer thickness [8] and temporal instabilities of the electric field [9]. However, recently high resistivity, chromium compensated gallium arsenide (HR-GaAs:Cr) [10] has shown to overcome the former restraints: high and uniformly distributed resistivity values [9], good electron charge transport properties [11], good spatial resolution as well as high image quality and signal-to-noise ratios close to the Poisson limit [12] were reported for this material which thus can be considered being a promising sensor material for X-ray applications up to around 40 keV [13][14][15]. Yet, to our knowledge, the high flux behavior of HR-GaAs:Cr, in particular in combination with photon counting readout chips, has not been investigated.…”

Section: Introductionmentioning

confidence: 99%

Investigation of GaAs:Cr Timepix assemblies under high flux irradiation

et al. 2015

Self Cite

View full text Add to dashboard Cite

High resistivity, chromium compensated gallium arsenide (HR-GaAs:Cr) has recently shown to be a promising sensor material for X-ray detectors due to its high resistivity, its fully active volume, the good electron transport properties and good absorption properties for photon energies up to around 40 keV. These properties make this material a favorable candidate for producing sensors for photon counting X-ray imaging detectors. Such detector systems have also gained increasing attention to be used for high flux applications as found at synchrotrons or in medical applications like computed tomography. Whereas other interesting high-Z materials such as CdTe have already been studied under high flux irradiation, the behavior of HR-GaAs:Cr under such conditions has yet to be investigated.In this work, we study the performance of a 500 µm thick GaAs:Cr sensor, bump-bonded to Timepix readout electronics, with a main emphasis laid on the behavior under the irradiation of high X-ray fluxes using a monochromatic synchrotron beam. We find that, at high X-ray fluxes, the detector performance degrades, and that the dislocation network typically present in melt-grown GaAs influences the detection properties due to local variations of the charge transport properties. However, we also demonstrate that the high flux behavior can be substantially improved by optimized chip settings, namely by tuning the Timepix' preamplifier output pulse shape. In this way, the photon counting capabilities of the detector assembly are restored to a certain extent and it is possible to operate the detector assembly at impinging fluxes as high as 10 10 s −1 mm −2 .

show abstract

GaAs Pixel Detectors

Cited by 7 publications

References 5 publications

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

Characterization of chromium compensated GaAs as an X-ray sensor material for charge-integrating pixel array detectors

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

Investigation of GaAs:Cr Timepix assemblies under high flux irradiation

Contact Info

Product

Resources

About