Spectral Response of THM Grown CdZnTe Crystals

Chen, H.; Awadalla, Salah; Harris, F. A.; Lu, P. H.; Redden, R.; Bindley, Glenn; Copete, A.; Hong, J.; Grindlay, Jonathan E.; Amman, M.; Lee, J.S.; Luke, P.N.; Kuvvetli, I.; Budtz-Jørgensen, Carl

doi:10.1109/tns.2008.924089

Cited by 37 publications

(22 citation statements)

References 33 publications

(10 reference statements)

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“…A further advantage of CZT is that the material can be manufactured into different shapes, for example co-planar grids and small pixel detectors to optimize for differing applications. This therefore improves detection characteristics (Table 2) (Luke et al 2001;Luke 1995;Wilson et al 2011), however the co-planar grid variation produces the best energy resolution of any of the detectors previously discussed (<2.5% at 662 keV) (Chen et al 2008;Martin et al 2015;Sellin 2003;Zhang et al 2013), allowing for the production of the most resolved energy spectrum and hence the most confident identification of individual radionuclides (although Table 2 indicates that this could still be improved upon). Despite this high resolution, problems with the uniformity of the crystal structure, such as random grain boundaries, have limited its effectiveness by causing charge trapping -reducing the counting efficiency in certain applications and limiting the volume of the detectors to small sizes, i.e.…”

Section: Detector Systems In Uav Radiometric Surveysmentioning

confidence: 99%

Airborne radiation mapping: overview and application of current and future aerial systems

Connor

Martin

Scott

2016

International Journal of Remote Sensing

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Nuclear power and associated activities are never far from scrutiny, the apparent advantages of the technology are juxtaposed by the risk of incidents perceived as being catastrophic. If a major nuclear incident was to occur, an important aspect of the response management to any radionuclide release would be the need to rapidly establish the spatial distributions and quantities of these released radionuclides, their type in addition to their corresponding activity. The data received from surveys would directly inform evacuation plans, on-site incident management strategies as well as protecting both workforce and public from harm. The disaster at the Fukushima Daiichi Nuclear Power Plant in 2011 is perhaps the best example of the requirement for real time data collection to inform crucial decisions. Previous reviews of the event have observed that because the static on-site radiation detector network was destroyed by the 15 m high tsunami (following the magnitude 9.0 Great Tōhoku earthquake), it was not possible to immediately determine the radionuclide activity in the area and the danger presented to the responding workforce. Such preceding works have retrospectively highlighted the usefulness of unmanned aerial systems in providing real-time data within nuclear and non-nuclear settings. The establishment of an arbitrary 20 km exclusion zone surrounding the Fukushima Daiichi plant, with the displacement of over 150,000 people, has been viewed by many as an over-reaction -with many not having been required to be evacuated. This review examines and evaluates the previous as well as current work on aerial radiation monitoring and the future improvement that might be delivered by a combined three-dimensional (3D) radiation mapping platform. Combining detailed 3D topographical mapping with radiation surveying has powerful implications for the way that radiological contamination across a site might be measured and displayed in the future, both following radiological release events and in routine site monitoring. • Comprehensive review of airborne radiation mapping.• Exploration of potential future systems.• Comparison of the multiple flight, mapping, and detection systems.• Application of devices to a range of scenarios.

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Section: Detector Systems In Uav Radiometric Surveysmentioning

confidence: 99%

Airborne radiation mapping: overview and application of current and future aerial systems

Connor

Martin

Scott

2016

International Journal of Remote Sensing

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“…A TCAD model of CZT was created by adding traps to a default CdTe model and raising the bandgap to 1.60eV. Simulations were conducted to identify a trapping scheme that produced realisitic resisitivity and charge transport, as reported in CZT bulk material [12][13][14].…”

Section: Modelling Czt Materialsmentioning

confidence: 99%

“…The range of experimental values of THM CZT [12][13][14] (µτ ) e is indicated; (µτ ) h of the same crystals was not reported. A mid-range value of µτ e = 3.5 × 10 −4 cm 2 /V was selected for the model.…”

Section: Modelling Realistic Charge Transportmentioning

confidence: 99%

“…It is desirable to replicate the excellent spectroscopic performance of silicon devices in a material with higher quantum efficiency for hard Xand gamma rays. Crystals grown by the Travelling Heater Method (THM) have recently become available and show evidence of superior spectroscopic qualities compared with previous material [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Charge transport optimization in CZT ring-drift detectors

Boothman¹,

Alruhaili²,

Veeramani³

et al. 2015

J. Phys. D: Appl. Phys.

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Abstract. Ring-Drift design has been applied to large (7.5mm×7.5mm×2.3mm) Cadmium Zinc Telluride (CZT) devices. This low-noise, single-carrier-sensing configuration is the gold standard for spectroscopic silicon X-ray detectors. By combining the advantages of Ring-Drift with the high quantum efficiency and room-temperature operating capabilities of CZT, a simple and compact device for high-resolution spectroscopy of X-rays in the range 50-500keV can be created. Quality of CZT crystals has improved greatly in recent years and electron-only sensing overcomes the problem of inherently poor hole transport in II-VI semiconductors.The spatial response of our 3-ring CZT device was studied by microbeam scanning while the voltages applied to all electrodes were systematically varied. Maximum active radius extended to 2.3mm, beyond the second ring. Resolution was limited by electronic noise. Our results show that the lateral field and its ratio to the bulk field exert a crucial influence on active area, peak position and sensitivity. CZT and the device geometry were modelled in 3D with Sentaurus TCAD. Line scans were simulated and trends in performance with bias conditions matched experimental data, validating the model. We aimed to optimise the resolution, sensitivity and active radius of the device. Fields and charge drift were visualised and the active volume was mapped in 3D to improve understanding of the factors governing performance including number of rings, their widths, positions and bias.

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“…CZT also has the pre-requisite detection properties like low leakage currents at high operating bias voltages, wide band gap (>1.5 eV at 300 K), high density (5.8 g/cm 3 ), which invariably made it a very suitable candidate for room-temperature nuclear radiation detection in the field of Homeland security, infrared focal plane arrays, space astronomy, environmental monitoring, and medical imaging applications. [3][4][5][6][7][8][9][10][11] Even with the advent of better crystal quality, CZT based materials suffer from poor charge-transport properties, especially due to holes. Presence of various kinds of defects is thought to be responsible for trapping of holes.…”

mentioning

confidence: 99%

Biparametric analyses of charge trapping in Cd0.9Zn0.1Te based virtual Frisch grid detectors

Chaudhuri

Zavalla

Krishna

et al. 2013

Journal of Applied Physics

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Detector grade Cd 0.9 Zn 0.1 Te (CZT) single crystals were grown from zone refined Cd, Zn, and Te ($7 N) precursor materials, using a tellurium solvent method. Detectors with virtual Frisch grid configuration were fabricated using these crystals. I-V measurements revealed low leakage currents at room-temperature, $11 nA for one such detector D1 and $8 nA for another detector D2 at 1100 V. The spectroscopic performances of the two CZT virtual Frisch grid detectors have been evaluated and compared for high energy gamma ray detection. Detector D1 showed a well-resolved pulse-height spectrum with an energy resolution of $1.6% for the 662 keV gamma rays. Detector D2 also showed a distinct 662 keV peak but with a broader pulse-height distribution. A digital biparametric correlation study of the depth of interaction and energy deposited by the 662 keV gamma rays was carried out. A different kind of correlation pattern from that observed normally for hole trapping was noticed in the case of detector D2. Correlation of results from thermally stimulated current measurement studies suggested that the anomalous biparametric correlation pattern was due to the trapping of holes but modified by the virtual Frisch grid effect. The results also suggested that the effect of electron trapping could not be ruled out either. Finally, a digital correction scheme was applied to recover the 137 Cs spectrum from the effect of charge loss. V C 2013 American Institute of Physics. [http://dx

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Spectral Response of THM Grown CdZnTe Crystals

Cited by 37 publications

References 33 publications

Airborne radiation mapping: overview and application of current and future aerial systems

Airborne radiation mapping: overview and application of current and future aerial systems

Charge transport optimization in CZT ring-drift detectors

Biparametric analyses of charge trapping in Cd0.9Zn0.1Te based virtual Frisch grid detectors

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