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Optimization Of Cadmium Zinc Telluride Crystal Growth For Room Temperature Radiation Detectors
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Book Synopsis Optimization of Cadmium Zinc Telluride Crystal Growth for Room Temperature Radiation Detectors by : Kelly Allan Jones
Download or read book Optimization of Cadmium Zinc Telluride Crystal Growth for Room Temperature Radiation Detectors written by Kelly Allan Jones and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Large Volume Single Crystal Growth of Cadmium Zinc Telluride with Minimal Secondary Phases for Room Temperature Radiation Detector Application by : Santosh Kumar Swain
Download or read book Large Volume Single Crystal Growth of Cadmium Zinc Telluride with Minimal Secondary Phases for Room Temperature Radiation Detector Application written by Santosh Kumar Swain and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Two major aspects of Cadmium Zinc Telluride (CdZnTe) crystal growth for room temperature radiation detection application namely tellurium rich second phase defects and single crystal yield have been addressed. Various approaches were considered towards the minimization of these defects both during growth and post growth thermal treatment in cadmium environment. Since the issue of retrograde solubility in CdZnTe pseudo binary alloy system causes tellurium precipitation, different cooling mechanisms were also devised to achieve minimal secondary phases. Some important and encouraging results were obtained relative to the size and distribution of secondary phases upon growing the crystal with different growth rate and different cooling rate of the crystal after growth. Thermomigration of tellurium were also observed while post processing samples in a temperature gradient, in (Cd, Zn) atmosphere. Results indicated orders of magnitude reduction on secondary phases at the expense of sample resistivity.
Book Synopsis Anweisung zur Ausführung des Titel III (Gewerbebetrieb im Umherziehen) der Gewerbe-Ordnung für den Norddeutschen Bund vom 21. Juni 1869 by :
Download or read book Anweisung zur Ausführung des Titel III (Gewerbebetrieb im Umherziehen) der Gewerbe-Ordnung für den Norddeutschen Bund vom 21. Juni 1869 written by and published by . This book was released on 1869 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of Traveling Heater Method to Grow Cadmium Telluride (CdTe)/Cadmium Zinc Telluride (CZT) Crystals by : Manchanahalli S. Rohan Rao
Download or read book Development of Traveling Heater Method to Grow Cadmium Telluride (CdTe)/Cadmium Zinc Telluride (CZT) Crystals written by Manchanahalli S. Rohan Rao and published by . This book was released on 2011 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Photoluminescence Characterization of Cadmium Zinc Telluride by : Mohamed Alshal
Download or read book Photoluminescence Characterization of Cadmium Zinc Telluride written by Mohamed Alshal and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The demand for wide bandgap semiconductors for radiation detector applications has significantly increased in recent years due to an ever-growing need for safeguard measures and medical imaging systems amongst other applications. The need for these devices to be portable and efficient, and to operate at room temperature is important for practical applications. For radiation detectors, the semiconductor materials are mainly required to have an optimal energy gap, high average atomic number, good electrical resistivity and charge transport properties as well as purity and homogeneity. Cadmium zinc telluride (CZT) distinctly stands out among the other choices of semiconductor materials for radiation detector applications, due to its attractive material properties and the room temperature operation possibility. A tremendous amount of research is being conducted to improve CZT technology and its implementation into more commercial systems. Applications of CZT detector technology in national security, high energy physics, nuclear spectroscopy, and medical imaging systems are of special interests. However, CZT devices still face challenges that need to be understood and overcome in order to have more efficient radiation detector systems. One such challenge lies in the understanding of the surfaces of CZT detectors and surface recombination effects on charge transport, charge collection efficiency, and detector performance. Another common issue is the degradation of CZT detectors due to the presence of defects which can act as traps for the charge carriers and cause incomplete charge collection from the detectors. Thus, a major challenge is that, the commercial CZT crystals have large concentrations of defects and impurities that need to be characterized, and their effects on the detector performance should be studied. Photoluminescence (PL) spectroscopy is a sensitive, non-contact and non-destructive method, suitable to characterize lower concentrations of point defects, such as substitutional impurities (donors, acceptors) and native defects in CZT crystals. A PL spectrum provides information regarding the defect nature of the crystal by determining the presence and the type of vacancies, interstitials, and impurities in the lattice. The main objective of this thesis is to address the presence of the defects in CZT crystals, identify their types, and study their roles in the performance of x-ray radiation detectors using PL spectroscopy. Additionally, using PL method and different excitation sources including UV excitation, this thesis studies the surface of CZT samples and investigates the PL signature of the surface oxide of the samples, in an effort to optimize the surface processing and thereby improve CZT detector performance.
Book Synopsis Study on Thermal Annealing of Cadmium Zinc Telluride (CZT) Crystals by :
Download or read book Study on Thermal Annealing of Cadmium Zinc Telluride (CZT) Crystals written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium Zinc Telluride (CZT) has attracted increasing interest with its promising potential as a room-temperature nuclear-radiation-detector material. However, different defects in CZT crystals, especially Te inclusions and dislocations, can degrade the performance of CZT detectors. Post-growth annealing is a good approach potentially to eliminate the deleterious influence of these defects. At Brookhaven National Laboratory (BNL), we built up different facilities for investigating post-growth annealing of CZT. Here, we report our latest experimental results. Cd-vapor annealing reduces the density of Te inclusions, while large temperature gradient promotes the migration of small-size Te inclusions. Simultaneously, the annealing lowers the density of dislocations. However, only-Cd-vapor annealing decreases the resistivity, possibly reflecting the introduction of extra Cd in the lattice. Subsequent Te-vapor annealing is needed to ensure the recovery of the resistivity after removing the Te inclusions.
Book Synopsis High-Z Materials for X-ray Detection by : Leonardo Abbene
Download or read book High-Z Materials for X-ray Detection written by Leonardo Abbene and published by Springer Nature. This book was released on 2023-01-01 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will provide readers with a good overview of some of most recent advances in the field of High-Z materials. There will be a good mixture of general chapters in both technology and applications in opto-electronics, X-ray detection and emerging optoelectronics applications. The book will have an in-depth review of the research topics from world-leading specialists in the field.
Book Synopsis Strategic Approaches Towards Solving Critical Challenges in Crystal Growth of Detector Grade Cd0.9Zn0.1Te Including Melt Mixing Techniques by : Amlan Datta
Download or read book Strategic Approaches Towards Solving Critical Challenges in Crystal Growth of Detector Grade Cd0.9Zn0.1Te Including Melt Mixing Techniques written by Amlan Datta and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last few decades Cadmium Zinc Telluride (CZT) has emerged as a novel material for radiation detection in homeland security as well as medical applications and as substrates for epitaxial growth of infrared detector, Mercury Cadmium Telluride. There are, however, several critical issues regarding the bulk growth of CZT which renders it unsuitable or cost ineffective for these applications. These challenges can be summarized as non-uniformity (due to Zinc and intentional dopant segregation), longer growth times (because of lower thermal conductivity of the melt), Tellurium (Te) secondary phases (SP), unstable growth interface (due to lower thermal conductivity and higher heat of fusion) and non-stoichiometric growth conditions. Systematic approaches towards solving these problems will be discussed along with the consequences and future research directions.
Book Synopsis Developments in Cadmium Zinc Telluride Crystal Growth, Sample Preparation and Characterisation [sic] Techniques by : Amlan Datta
Download or read book Developments in Cadmium Zinc Telluride Crystal Growth, Sample Preparation and Characterisation [sic] Techniques written by Amlan Datta and published by . This book was released on 2010 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advanced Materials for Radiation Detection by : Krzysztof (Kris) Iniewski
Download or read book Advanced Materials for Radiation Detection written by Krzysztof (Kris) Iniewski and published by Springer Nature. This book was released on 2021-08-05 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers readers an overview of some of the most recent advances in the field of advanced materials used for gamma and X-ray imaging. Coverage includes both technology and applications, with an in-depth review of the research topics from leading specialists in the field. Emphasis is on high-Z materials like CdTe, CZT and GaAs, as well as perovskite crystals, since they offer the best implementation possibilities for direct conversion X-ray detectors. Authors discuss material challenges, detector operation physics and technology and readout integrated circuits required to detect signals processes by high-Z sensors.
Book Synopsis Material Properties of Large-volume Cadmium Zinc Telluride Crystals and Their Relationship to Nuclear Detector Performance by :
Download or read book Material Properties of Large-volume Cadmium Zinc Telluride Crystals and Their Relationship to Nuclear Detector Performance written by and published by . This book was released on 1997 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The material showing the greatest promise today for production of large-volume gamma-ray spectrometers operable at room temperature is cadmium zinc telluride (CZT). Unfortunately, because of deficiencies in the quality of the present material, high-resolution CZT spectrometers have thus far been limited to relatively small dimensions, which makes them inefficient at detecting high photon energies and ineffective for weak radiation signals except in near proximity. To exploit CZT fully, it will be necessary to make substantial improvements in the material quality. Improving the material involves advances in the purity, crystallinity, and control of the electrical compensation mechanism. Sandia National Laboratories, California, in close collaboration with US industry and academia, has initiated efforts to develop a detailed understanding of the underlying material problems limiting the performance of large volume gamma-ray spectrometers and to overcome them through appropriate corrections therein. A variety of analytical and numerical techniques are employed to quantify impurities, compositional and stoichiometric variations, crystallinity, strain, bulk and surface defect states, carrier mobilities and lifetimes, electric field distributions, and contact chemistry. Data from these measurements are correlated with spatial maps of the gamma-ray and alpha particle spectroscopic response to determine improvements in the material purification, crystal growth, detector fabrication, and surface passivation procedures. The results of several analytical techniques will be discussed. The intended accomplishment of this work is to develop a low-cost, high-efficiency CZT spectrometer with an active volume of 5 cm3 and energy resolution of 1--2% (at 662 keV), which would give the US a new field capability for screening radioactive substances.
Book Synopsis Strategies and Challenges to Improve Single Crystal Yield and Detector Properties of Cadmium Zinc Telluirde [that Is, Telluride] Grown Via Accelerated Crucible Rotation by : Saketh Kakkireni
Download or read book Strategies and Challenges to Improve Single Crystal Yield and Detector Properties of Cadmium Zinc Telluirde [that Is, Telluride] Grown Via Accelerated Crucible Rotation written by Saketh Kakkireni and published by . This book was released on 2020 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid-state radiation detection finds its applications in numerous fields ranging from nuclear medicine to astrophysics. Although Semiconductors offer better energy and spatial resolution than Scintillators, their market share is limited by the cost, availability and need for cryogenic cooling. Cadmium Zinc Telluride (CZT) is a compound semiconductor with attractive properties for compact device technology for detection of X-rays and Gamma-rays. Over the past few decades' numerous efforts are made to grow high-quality CZT, unfortunately to-date it's application is limited by large-scale production and cost. Poor thermo-physical properties of CZT coupled with no strong growth direction make it a challenge to achieve high yield of single crystalline material. Current industrial flux growth technique is inherently limited by slow growth rates and requires post-processing. The solution may be found in the Accelerated Crucible Rotation Technique (ACRT), where the crystal growth is achieved under a forced convective regime involving periodic rotation of the growth crucible. ACRT induced flow patterns can homogenize the melt thereby enabling faster growth rates and eliminate the need for post-processing. Our preliminary results, presented here, show that ACRT can reduce the production time by a factor of four. Additionally, the application of ACRT has provided the potential for scale up the growth process. Also discussed are challenges and future strategies in ACRT coupled CZT growth. Successful completion of this work will enable the use of CZT in the next generation imaging systems as well as provide a better foundation for understanding and implementing ACRT in other crystal growth systems. Successful seeding and superior detector resolutions are demonstrated.
Book Synopsis Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors by :
Download or read book Post-Growth Annealing of Bridgman-grown CdZnTe and CdMnTe Crystals for Room-temperature Nuclear Radiation Detectors written by and published by . This book was released on 2015 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray- and gamma-ray-detectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 °C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 °C in Cd vapor for 26 h, whilst their electrical resistivity fell by an order of 102. During the temperature-gradient annealing of CMT at 730 °C and an 18 °C/cm temperature gradient for 18 h in a vacuum of 10-5 mbar, we observed the diffusion of Te from the sample, causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 °C in a 10 °C/cm temperature gradient, we observed the migration of Te inclusions from a low-temperature region to a high one at 0.022 [mu]m/s. During the temperature-gradient annealing of CZT in a vacuum of 10-5 mbar at 570 °C and 30 °C/cm for 18 h, some Te inclusions moved toward the high-temperature side of the wafer, while other inclusions of the same size, i.e., 10 μm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT- and CMT-wafers are complex phenomena that depend on certain conditions.
Book Synopsis Characterization of Te Secondary Phases in Cadmium Zinc Telluride Using IR Transmission Microscopy by : W. Gitau Munge
Download or read book Characterization of Te Secondary Phases in Cadmium Zinc Telluride Using IR Transmission Microscopy written by W. Gitau Munge and published by . This book was released on 2010 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigations of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection by :
Download or read book Investigations of Cadmium Manganese Telluride Crystals for Room-Temperature Radiation Detection written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium manganese telluride (CMT) has high potential as a material for room-temperature nuclear-radiation detectors. We investigated indium-doped CMT crystals taken from the stable growth region of the ingot, and compared its characteristics with that from the last-to-freeze region. We employed different techniques, including synchrotron white-beam X-ray topography (SWBXT), current-voltage (I-V) measurements, and low-temperature photoluminescence spectra, and we also assessed their responses as detectors to irradiation exposure. The crystal from the stable growth region proved superior to that from the last-to-freeze region; it is a single-grain crystal, free of twins, and displayed a resistivity higher by two orders-of-magnitude. The segregation of indium dopant in the ingot might be responsible for its better resistivity. Furthermore, we recorded a good response in the detector fabricated from the crystal taken from the stable growth region; its ([mu][tau]){sub e} value was 2.6 x 10−3 cm2/V, which is acceptable for thin detectors, including for applications in medicine.
Book Synopsis Cadmium Telluride and Cadmium Zinc Telluride Detectors for Radionuclide Analysis by : Anthony Drew Lavietes
Download or read book Cadmium Telluride and Cadmium Zinc Telluride Detectors for Radionuclide Analysis written by Anthony Drew Lavietes and published by . This book was released on 1995 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Implementation of Accelerated Crucible Rotation in Electrodynamic Gradient Freeze Method for Highly Non-stoichiometric Melt Growth of Cadmium Zinc Telluride Detectors by : Jedidiah Jacob McCoy
Download or read book Implementation of Accelerated Crucible Rotation in Electrodynamic Gradient Freeze Method for Highly Non-stoichiometric Melt Growth of Cadmium Zinc Telluride Detectors written by Jedidiah Jacob McCoy and published by . This book was released on 2018 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium Zinc Telluride (CZT) is a semiconducting material well known in the high energy radiation detection community for its virtues as a solid state radiation detector. Its application is broad, spanning homeland security, nonproliferation, medical physics, and astrophysics. Unfortunately, difficulty in producing detector grade CZT in appreciable quantities has greatly limited its economic success. Several decades have been spent on overcoming this production issue, but with little success. At present, the traveling heater method (THM) is most widely used for industrial growth applications as it can produce detector grade material with acceptable yields. However, CZT growth rates in THM remain relatively slow, and post-growth processing is required resulting in long, economically disadvantaged timescales. On the other hand, melt growth techniques, such as vertical Bridgman (VB) and its modifications, are capable of much faster growth rates, but suffer from low yields and poor reproducibility. Additionally, electron mobility lifetime (microtaue) products from VB grown CZT have traditionally been an order of magnitude lower than THM grown CZT. Even so, because of its fast growth rate, VB is the ideal candidate to achieve economic success in CZT production if reproducible material yield and competitive microtau e products can be achieved. To accomplish this, the following set of issues inherent to melt growth of CZT must be addressed: inhomogeneity in Zn and dopant concentrations, the presence of second phase defects, low single crystal yield, and high impurity content. This dissertation will outline the development of a mode for bulk CZT production via VB method capable of overcoming these four melt growth issues. Accelerated Crucible Rotation (ACRT) was implemented during growth in order to homogenize the melt and adjust interface stability. A systematic study was conducted with computational guidance to optimize ACRT parameters. Melt stoichiometry was adjusted to enhance ACRT mixing as well as adjust maximum growth temperatures and improve overall purity. Temperature profile and material handling procedures were optimized as well. The developed method is capable of producing highly competitive detector grade CZT material with unprecedented yields on economically viable timescales.
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