Energy-loss correction in charge sharing events for improved performance of pixellated compound semiconductors

Bugby, Sarah L.; Koch-Mehrin, Kjell A. L.; Veale, Matthew C.; Wilson, Matthew D.; Lees, J.E.

doi:10.1016/j.nima.2019.06.017

Cited by 28 publications

(45 citation statements)

References 18 publications

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“…This levelling-off is observed in the measured FWHM and σ c values for the multi-pixel events in both detectors (Figure 7). A similar trend with energy has been observed by Bugby et al [36] in calculations of a charge loss correction parameter. Average interaction depth for photons of different energy in a 1 mm and 2 mm block of CdTe and CdZnTe, respectively.…”

Section: Depth Of Interaction and Charge Loss Correlationsupporting

confidence: 87%

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Koch-Mehrin

Bugby

Lees

et al. 2021

Sensors

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Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (>1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch and 25 μm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field.

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Section: Depth Of Interaction and Charge Loss Correlationsupporting

confidence: 87%

Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Koch-Mehrin

Bugby

Lees

et al. 2021

Sensors

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“…The charge loss is a result of a lower field region between pixels that results in additional charge trapping. This phenomenon has been studied previously in HEXITEC devices and is beyond the scope of this paper [ 24 , 25 , 26 ].…”

Section: Resultsmentioning

confidence: 94%

Characterization of the Uniformity of High-Flux CdZnTe Material

Veale

Booker

Cross

et al. 2020

Sensors

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Since the late 2000s, the availability of high-quality cadmium zinc telluride (CdZnTe) has greatly increased. The excellent spectroscopic performance of this material has enabled the development of detectors with volumes exceeding 1 cm3 for use in the detection of nuclear materials. CdZnTe is also of great interest to the photon science community for applications in X-ray imaging cameras at synchrotron light sources and free electron lasers. Historically, spatial variations in the crystal properties and temporal instabilities under high-intensity irradiation has limited the use of CdZnTe detectors in these applications. Recently, Redlen Technologies have developed high-flux-capable CdZnTe material (HF-CdZnTe), which promises improved spatial and temporal stability. In this paper, the results of the characterization of 10 HF-CdZnTe detectors with dimensions of 20.35 mm × 20.45 mm × 2.00 mm are presented. Each sensor has 80 × 80 pixels on a 250-μm pitch and were flip-chip-bonded to the STFC HEXITEC ASIC. These devices show excellent spectroscopic performance at room temperature, with an average Full Width at Half Maximum (FWHM) of 0.83 keV measured at 59.54 keV. The effect of tellurium inclusions in these devices was found to be negligible; however, some detectors did show significant concentrations of scratches and dislocation walls. An investigation of the detector stability over 12 h of continuous operation showed negligible changes in performance.

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“…The average size of the charge cluster created by an x-ray interaction in a CdTe crystal was reported to be on the order of ~10 μm [14], thus the less separation between the neighboring pixels, the higher the probability of the charge sharing effect. To address this issue, HEXITEC offers two correction algorithms for the charge sharing effect: charge sharing discrimination (CSD) and charge sharing addition (CSA) [17,18]. Fig.…”

Section: Effect Of Charge Sharing On the Acquired Spectramentioning

confidence: 99%