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Principato F, Bettelli M, Zappettini A, Abbene L. A Novel Extraction Procedure of Contact Characteristic Parameters from Current-Voltage Curves in CdZnTe and CdTe Detectors. SENSORS (BASEL, SWITZERLAND) 2023; 23:6075. [PMID: 37447923 DOI: 10.3390/s23136075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023]
Abstract
The estimation of the characteristic parameters of the electrical contacts in CdZnTe and CdTe detectors is related to the identification of the main transport mechanisms dominating the currents. These investigations are typically approached by modelling the current-voltage (I-V) curves with the interfacial layer-thermionic-diffusion (ITD) theory, which incorporates the thermionic emission, diffusion and interfacial layer theories into a single theory. The implementation of the ITD model in measured I-V curves is a critical procedure, requiring dedicated simplifications, several best fitting parameters and the identification of the voltage range where each transport mechanism dominates. In this work, we will present a novel method allowing through a simple procedure the estimation of some characteristic parameters of the metal-semiconductor interface in CdZnTe and CdTe detectors. The barrier height and the effects of the interfacial layer will be evaluated through the application of a new function related to the differentiation of the experimental I-V curves.
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Affiliation(s)
- Fabio Principato
- Department of Physics and Chemistry (DiFC)-Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy
| | | | | | - Leonardo Abbene
- Department of Physics and Chemistry (DiFC)-Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy
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2
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Yang C, Zannoni EM, Meng LJ. Joint estimation of interaction position and energy deposition in semiconductor SPECT imaging sensors using fully connected neural network. Phys Med Biol 2023; 68:10.1088/1361-6560/aca740. [PMID: 36595331 PMCID: PMC10329845 DOI: 10.1088/1361-6560/aca740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 11/29/2022] [Indexed: 12/02/2022]
Abstract
Objective.Pixelated semiconductor detectors such as CdTe and CZT sensors suffer spatial resolution and spectral performance degradation induced by charge-sharing effects. It is critical to enhance the detector property through recovering the energy-deposition and position estimation.Approach.In this work, we proposed a fully-connected-neural-network-based charge-sharing reconstruction algorithm to correct the charge-loss and estimate the sub-pixel position for every multi-pixel charge-sharing event.Main results.Evident energy resolution improvement can be observed by comparing the spectrum produced by a simple charge-sharing addition method and the proposed energy correction methods. We also demonstrate that sub-pixel resolution can be achieved in projections obtained with a small pinhole collimator and an innovative micro-ring collimator.Significance.These achievements are crucial for multiple-tracer SPECT imaging applications, and for other semiconductor detector-based imaging modalities.
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Affiliation(s)
- Can Yang
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, United States of America
| | - Elena Maria Zannoni
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, United States of America
| | - Ling-Jian Meng
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, United States of America
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, United States of America
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States of America
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3
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Buttacavoli A, Principato F, Gerardi G, Cascio D, Raso G, Bettelli M, Zappettini A, Taormina V, Abbene L. Window-Based Energy Selecting X-ray Imaging and Charge Sharing in Cadmium Zinc Telluride Linear Array Detectors for Contaminant Detection. SENSORS (BASEL, SWITZERLAND) 2023; 23:3196. [PMID: 36991907 PMCID: PMC10054609 DOI: 10.3390/s23063196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/09/2023] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
The spectroscopic and imaging performance of energy-resolved photon counting detectors, based on new sub-millimetre boron oxide encapsulated vertical Bridgman cadmium zinc telluride linear arrays, are presented in this work. The activities are in the framework of the AVATAR X project, planning the development of X-ray scanners for contaminant detection in food industry. The detectors, characterized by high spatial (250 µm) and energy (<3 keV) resolution, allow spectral X-ray imaging with interesting image quality improvements. The effects of charge sharing and energy-resolved techniques on contrast-to-noise ratio (CNR) enhancements are investigated. The benefits of a new energy-resolved X-ray imaging approach, termed window-based energy selecting, in the detection of low- and high-density contaminants are also shown.
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Affiliation(s)
- Antonino Buttacavoli
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
| | - Fabio Principato
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
| | - Gaetano Gerardi
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
| | - Donato Cascio
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
| | - Giuseppe Raso
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
| | | | | | - Vincenzo Taormina
- Department of Mathematics and Informatics, University of Palermo, 90123 Palermo, Italy
| | - Leonardo Abbene
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, 90128 Palermo, Italy; (A.B.)
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Buttacavoli A, Principato F, Gerardi G, Bettelli M, Zappettini A, Seller P, Veale MC, Zanettini S, Abbene L. Ballistic Deficit Pulse Processing in Cadmium-Zinc-Telluride Pixel Detectors for High-Flux X-ray Measurements. SENSORS 2022; 22:s22093409. [PMID: 35591099 PMCID: PMC9103549 DOI: 10.3390/s22093409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/24/2022] [Accepted: 04/27/2022] [Indexed: 01/25/2023]
Abstract
High-flux X-ray measurements with high-energy resolution and high throughput require the mitigation of pile-up and dead time effects. The reduction of the time width of the shaped pulses is a key approach, taking into account the distortions from the ballistic deficit, non-linearity, and time instabilities. In this work, we will present the performance of cadmium−zinc−telluride (CdZnTe or CZT) pixel detectors equipped with digital shapers faster than the preamplifier peaking times (ballistic deficit pulse processing). The effects on energy resolution, throughput, energy-linearity, time stability, charge sharing, and pile-up are shown. The results highlight the absence of time instabilities and high-energy resolution (<4% FWHM at 122 keV) when ballistic deficit pulse processing (dead time of 90 ns) was used in CZT pixel detectors. These activities are in the framework of an international collaboration on the development of spectroscopic imagers for medical applications (mammography, computed tomography) and non-destructive testing in the food industry.
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Affiliation(s)
- Antonino Buttacavoli
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.)
| | - Fabio Principato
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.)
| | - Gaetano Gerardi
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.)
| | - Manuele Bettelli
- IMEM/CNR, Parco Area delle Scienze 37/A, 43100 Parma, Italy; (M.B.); (A.Z.)
| | - Andrea Zappettini
- IMEM/CNR, Parco Area delle Scienze 37/A, 43100 Parma, Italy; (M.B.); (A.Z.)
| | - Paul Seller
- UKRI Science & Technology Facilities Council, Didcot OX11 0QX, UK; (P.S.); (M.C.V.)
| | - Matthew C. Veale
- UKRI Science & Technology Facilities Council, Didcot OX11 0QX, UK; (P.S.); (M.C.V.)
| | | | - Leonardo Abbene
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.)
- Correspondence:
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Buttacavoli A, Principato F, Gerardi G, Cascio D, Raso G, Bettelli M, Zappettini A, Seller P, Veale MC, Abbene L. Incomplete Charge Collection at Inter-Pixel Gap in Low- and High-Flux Cadmium Zinc Telluride Pixel Detectors. SENSORS 2022; 22:s22041441. [PMID: 35214342 PMCID: PMC8875842 DOI: 10.3390/s22041441] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/01/2023]
Abstract
The success of cadmium zinc telluride (CZT) detectors in room-temperature spectroscopic X-ray imaging is now widely accepted. The most common CZT detectors are characterized by enhanced-charge transport properties of electrons, with mobility-lifetime products μeτe > 10−2 cm2/V and μhτh > 10−5 cm2/V. These materials, typically termed low-flux LF-CZT, are successfully used for thick electron-sensing detectors and in low-flux conditions. Recently, new CZT materials with hole mobility-lifetime product enhancements (μhτh > 10−4 cm2/V and μeτe > 10−3 cm2/V) have been fabricated for high-flux measurements (high-flux HF-CZT detectors). In this work, we will present the performance and charge-sharing properties of sub-millimeter CZT pixel detectors based on LF-CZT and HF-CZT crystals. Experimental results from the measurement of energy spectra after charge-sharing addition (CSA) and from 2D X-ray mapping highlight the better charge-collection properties of HF-CZT detectors near the inter-pixel gaps. The successful mitigation of the effects of incomplete charge collection after CSA was also performed through original charge-sharing correction techniques. These activities exist in the framework of international collaboration on the development of energy-resolved X-ray scanners for medical applications and non-destructive testing in the food industry.
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Affiliation(s)
- Antonino Buttacavoli
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
| | - Fabio Principato
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
| | - Gaetano Gerardi
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
| | - Donato Cascio
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
| | - Giuseppe Raso
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
| | - Manuele Bettelli
- IMEM/CNR, Parco Area delle Scienze 37/A, 43100 Parma, Italy; (M.B.); (A.Z.)
| | - Andrea Zappettini
- IMEM/CNR, Parco Area delle Scienze 37/A, 43100 Parma, Italy; (M.B.); (A.Z.)
| | - Paul Seller
- Rutherford Appleton Laboratory, UKRI Science & Technology Facilities Council, Oxon OX11 0QX, UK; (P.S.); (M.C.V.)
| | - Matthew C. Veale
- Rutherford Appleton Laboratory, UKRI Science & Technology Facilities Council, Oxon OX11 0QX, UK; (P.S.); (M.C.V.)
| | - Leonardo Abbene
- Department of Physics and Chemistry (DiFC)—Emilio Segrè, University of Palermo, Viale Delle Scienze, Edificio 18, 90128 Palermo, Italy; (A.B.); (F.P.); (G.G.); (D.C.); (G.R.)
- Correspondence:
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Zhang Z, Ma YZ, Thomas L, Gofryk K, Saparov B. Physical Properties of Candidate X-Ray Detector Material Rb 4Ag 2BiBr 9. CRYSTAL GROWTH & DESIGN 2022; 22:1066-1072. [PMID: 36845267 PMCID: PMC9956939 DOI: 10.1021/acs.cgd.1c00986] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Recently, metal halide perovskites have emerged as promising semiconductor candidates for sensitive X-ray photon detection due to their suitable bandgap energies, excellent charge transport properties, and low material cost afforded by their low-temperature solution-processing preparation. Here, we report an improved methodology for single crystal (SC) growth, thermal and electrical properties of a two-dimensional (2D) layered halide material Rb4Ag2BiBr9, which has been identified as a potential candidate for X-ray radiation detection applications. The measured heat capacity for Rb4Ag2BiBr9 implies that there are no structural phase transitions upon cooling. Temperature dependence of thermal transport measurements further suggest remarkably low thermal conductivities of Rb4Ag2BiBr9 that are comparable to the lowest reported in literature. The bulk crystal resistivity is determined to be 2.59×109 Ω·cm from the current-voltage (I-V) curve. Density of trap states are estimated to be ~1010 cm-3 using the space-charge-limited-current (SCLC) measurements. The fabricated Rb4Ag2BiBr9-based X-ray detector shows good operational stability with no apparent current drift, which may be ascribed to the 2D crystal structure of Rb4Ag2BiBr9. Finally, by varying the X-ray tube current to change the corresponding dose rate, the Rb4Ag2BiBr9 X-ray detector sensitivity is determined to be 222.03 uCGy-1cm-2 (at an electric field of E = 24 V/mm).
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Affiliation(s)
- Zheng Zhang
- Department of Chemistry & Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Ying-Zhong Ma
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Leonard Thomas
- Department of Chemistry & Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
| | - Krzysztof Gofryk
- Idaho National Laboratory, Idaho Falls, Idaho 83415, United States
| | - Bayram Saparov
- Department of Chemistry & Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States
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Datta A, Fiala J, Motakef S. 2D perovskite-based high spatial resolution X-ray detectors. Sci Rep 2021; 11:22897. [PMID: 34819595 PMCID: PMC8613224 DOI: 10.1038/s41598-021-02378-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 11/15/2021] [Indexed: 11/24/2022] Open
Abstract
X-ray radiography is the most widely used imaging technique with applications encompassing medical and industrial imaging, homeland security, and materials research. Although a significant amount of research and development has gone into improving the spatial resolution of the current state-of-the-art indirect X-ray detectors, it is still limited by the detector thickness and microcolumnar structure quality. This paper demonstrates high spatial resolution X-ray imaging with solution-processable two-dimensional hybrid perovskite single-crystal scintillators grown inside microcapillary channels as small as 20 µm. These highly scalable non-hygroscopic detectors demonstrate excellent spatial resolution similar to the direct X-ray detectors. X-ray imaging results of a camera constructed using this scintillator show Modulation Transfer Function values significantly better than the current state-of-the-art X-ray detectors. These structured detectors open up a new era of low-cost large-area ultrahigh spatial resolution high frame rate X-ray imaging with numerous applications.
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Affiliation(s)
- Amlan Datta
- CapeSym, Inc., 6 Huron Drive, Natick, MA, 01760, USA.
| | - John Fiala
- CapeSym, Inc., 6 Huron Drive, Natick, MA, 01760, USA
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