High voltage optimization in CdZnTe detectors

Awadalla, Salah; AL-Grafi, Mubarak; Iniewski, Krzysztof

doi:10.1016/j.nima.2014.07.026

Cited by 19 publications

(12 citation statements)

References 10 publications

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“…A CZT pixel detector with different anode arrays was fabricated by IMEM-CNR (Parma, Italy; http://www.imem.cnr.it) and due2lab s.r.l (Reggio Emilia, Italy; http://www.due2 lab.com). The detector is based on a CZT crystal (4.25 Â 3.25 Â 2 mm), grown by Redlen Technologies (Victoria BC, Canada; http://redlen.ca) using the travelling heater method (THM) technique (Awadalla et al, 2014;Chen et al, 2007Chen et al, , 2008. Gold electroless contacts were realized on both the anode and the cathode of the detectors.…”

Section: Czt Pixel Detectormentioning

confidence: 99%

Digital fast pulse shape and height analysis on cadmium–zinc–telluride arrays for high-flux energy-resolved X-ray imaging

et al. 2018

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Cadmium-zinc-telluride (CZT) arrays with photon-counting and energy-resolving capabilities are widely proposed for next-generation X-ray imaging systems. This work presents the performance of a 2 mm-thick CZT pixel detector, with pixel pitches of 500 and 250 µm, dc coupled to a fast and low-noise ASIC (PIXIE ASIC), characterized only by the preamplifier stage. A custom 16-channel digital readout electronics was used, able to digitize and process continuously the signals from each output ASIC channel. The digital system performs on-line fast pulse shape and height analysis, with a low dead-time and reasonable energy resolution at both low and high fluxes. The spectroscopic response of the system to photon energies below (Cd source) and above (Am source) the K-shell absorption energy of the CZT material was investigated, with particular attention to the mitigation of charge sharing and pile-up. The detector allows high bias voltage operation (>5000 V cm) and good energy resolution at moderate cooling (3.5% and 5% FWHM at 59.5 keV for the 500 and 250 µm arrays, respectively) by using fast pulse shaping with a low dead-time (300 ns). Charge-sharing investigations were performed using a fine time coincidence analysis (TCA), with very short coincidence time windows up to 10 ns. For the 500 µm pitch array (250 µm pitch array), sharing percentages of 36% (52%) and 60% (82%) at 22.1 and 59.5 keV, respectively, were measured. The potential of the pulse shape analysis technique for charge-sharing detection for corner/border pixels and at high rate conditions (250 kcps pixel), where the TCA fails, is also shown. Measurements demonstrated that significant amounts of charge are lost for interactions occurring in the volume of the inter-pixel gap. This charge loss must be accounted for in the correction of shared events. These activities are within the framework of an international collaboration on the development of energy-resolved photon-counting systems for high-flux energy-resolved X-ray imaging (1-140 keV).

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Section: Czt Pixel Detectormentioning

confidence: 99%

Digital fast pulse shape and height analysis on cadmium–zinc–telluride arrays for high-flux energy-resolved X-ray imaging

et al. 2018

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“…The shape and the height of these pulses were analysed and their role in the mitigation of charge losses in CZT pixel detectors. based on CZT crystals (4.25 mm Â 3.25 mm Â 1 mm; 4.25 mm Â 3.25 mm Â 2 mm), grown by Redlen Technologies (Victoria BC, Canada; http://redlen.ca) with the travelling heater method (THM) technique (Awadalla et al, 2014;Chen et al, 2007Chen et al, , 2008. In the last decade, spectroscopic-grade CZT crystals with excellent electron charge transport properties ( e e > 10 À2 cm 2 V À1 ; h h ' 10 À5 cm 2 V À1 ) have been routinely produced by Redlen.…”

Section: Introductionmentioning

confidence: 99%

Dual-polarity pulse processing and analysis for charge-loss correction in cadmium–zinc–telluride pixel detectors

et al. 2018

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Charge losses at the inter-pixel gap are typical drawbacks in cadmium-zinc-telluride (CZT) pixel detectors. In this work, an original technique able to correct charge losses occurring after the application of charge-sharing addition (CSA) is presented. The method, exploiting the strong relation between the energy after CSA and the beam position at the inter-pixel gap, allows the recovery of charge losses and improvements in energy resolution. Sub-millimetre CZT pixel detectors were investigated with both uncollimated radiation sources and collimated synchrotron X-rays, at energies below and above the K-shell absorption energy of the CZT material. The detectors are DC coupled to fast and low-noise charge-sensitive preamplifiers (PIXIE ASIC) and followed by a 16-channel digital readout electronics, performing multi-parameter analysis (event arrival time, pulse shape, pulse height). Induced-charge pulses with negative polarity were also observed in the waveforms from the charge-sensitive preamplifiers (CSPs) at energies >60 keV. The shape and the height of these pulses were analysed, and their role in the mitigation of charge losses in CZT pixel detectors. These activities are in the framework of an international collaboration on the development of energy-resolved photon-counting systems for spectroscopic X-ray imaging (5-140 keV).

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“…Details about the MOVPE growth of thick single crystal CdZnTe layers on (211) Si substrates are also presented (Niraula et al 2013). Cd 0.9 Zn 0.1 Te (Awadalla et al 2014) and CdZnTe (Roy et al 2013) layers have been grown using the traveling heater method (THM). A series of Cu doped Cd 1-x Zn x Te thin films have also been deposited on quartz substrates by magnetron cosputtering and their properties have been investigated (Wu 2013).…”

Section: Introductionmentioning

confidence: 99%

Efficiency improvement of CdZnTe solar cell by modification of interface layer

Rezaie

Kosarian

2015

Opt Quant Electron

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Solar conversion efficiency of graded Cd 1-x Zn x Te solar cells is investigated numerically in this work. It is found that the efficiency can be improved if a p-Cd 0.6 Zn 0.4 Te layer is added to the basic n-ZnO/n-CdS/p-CdTe structure. On the other hand, there is a sharp conduction band offset at the interface of the CdTe and p-Cd 0.6 Zn 0.4 Te layer that affects the cell performance. At the next step, in order to remove the discontinuity at the conduction band between p-CdTe and p-Cd 0.6 Zn 0.4 Te, we have replaced the Cd 1-x Zn x Te with a graded region where the Cd 1-x Zn x Te layer is divided into several individual thinner layers. As a result, the electron (minority carrier) collection at the hetero-interface improves, duo to the establishment of an extra electric field across the graded region, leading to an increase in the solar conversion efficiency. The number of layers and doping concentration of the graded region plays an important role in the performance of the cell. Finally, it had been found that the ZnO/CdS/CdTe/Cd 1-x Zn x Te/p-Cd 0.6 Zn 0.4 Te structure in which the Cd 1-x Zn x Te region consists of 25 thin layers with 10 18 cm -3 doping concentration will have an efficiency &1 % higher than that of the ungraded ZnO/CdS/CdTe structure.

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High voltage optimization in CdZnTe detectors

Cited by 19 publications

References 10 publications

Digital fast pulse shape and height analysis on cadmium–zinc–telluride arrays for high-flux energy-resolved X-ray imaging

Digital fast pulse shape and height analysis on cadmium–zinc–telluride arrays for high-flux energy-resolved X-ray imaging

Dual-polarity pulse processing and analysis for charge-loss correction in cadmium–zinc–telluride pixel detectors

Efficiency improvement of CdZnTe solar cell by modification of interface layer

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