Strategies And Challenges To Improve Single Crystal Yield And Detector Properties Of Cadmium Zinc Telluirde That Is Telluride Grown Via Accelerated Crucible Rotation

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Strategies and Challenges to Improve Single Crystal Yield and Detector Properties of Cadmium Zinc Telluirde [that Is, Telluride] Grown Via Accelerated Crucible Rotation

Author : Saketh Kakkireni
Publisher :
ISBN 13 :
Total Pages : 164 pages
Book Rating : 4.6/5 (985 download)

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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.

Implementation of Accelerated Crucible Rotation in Electrodynamic Gradient Freeze Method for Highly Non-stoichiometric Melt Growth of Cadmium Zinc Telluride Detectors

Download Implementation of Accelerated Crucible Rotation in Electrodynamic Gradient Freeze Method for Highly Non-stoichiometric Melt Growth of Cadmium Zinc Telluride Detectors PDF Online Free

Author : Jedidiah Jacob McCoy
Publisher :
ISBN 13 :
Total Pages : 164 pages
Book Rating : 4.:/5 (18 download)

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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.

Strategic Approaches Towards Solving Critical Challenges in Crystal Growth of Detector Grade Cd0.9Zn0.1Te Including Melt Mixing Techniques

Download Strategic Approaches Towards Solving Critical Challenges in Crystal Growth of Detector Grade Cd0.9Zn0.1Te Including Melt Mixing Techniques PDF Online Free

Author : Amlan Datta
Publisher :
ISBN 13 : 9781303240690
Total Pages : pages
Book Rating : 4.2/5 (46 download)

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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.

Large Volume Single Crystal Growth of Cadmium Zinc Telluride with Minimal Secondary Phases for Room Temperature Radiation Detector Application

Download Large Volume Single Crystal Growth of Cadmium Zinc Telluride with Minimal Secondary Phases for Room Temperature Radiation Detector Application PDF Online Free

Author : Santosh Kumar Swain
Publisher :
ISBN 13 : 9781267199249
Total Pages : pages
Book Rating : 4.1/5 (992 download)

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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.

Developments in Cadmium Zinc Telluride Crystal Growth, Sample Preparation and Characterisation [sic] Techniques

Author : Amlan Datta
Publisher :
ISBN 13 :
Total Pages : 97 pages
Book Rating : 4.:/5 (695 download)

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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:

Spatial Mapping of Cadmium Zinc Telluride Materials Properties and Electrical Response to Improve Device Yield and Performance

Author :
Publisher :
ISBN 13 :
Total Pages : 17 pages
Book Rating : 4.:/5 (684 download)

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Book Synopsis Spatial Mapping of Cadmium Zinc Telluride Materials Properties and Electrical Response to Improve Device Yield and Performance by :

Download or read book Spatial Mapping of Cadmium Zinc Telluride Materials Properties and Electrical Response to Improve Device Yield and Performance written by and published by . This book was released on 1998 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cadmium zinc telluride has experienced tremendous growth in its application to various radiation sensing problems over the last five years. However, there are still issues with yield, particularly of the large volume devices needed for imaging and sensitivity-critical applications. Inhomogeneities of various types and on various length scales currently prevent the fabrication of large devices of high spectral performance. This paper discusses the development of a set of characterization tools for quantifying these inhomogeneities, in order to develop improvement strategies to achieve the desired cadmium zinc telluride crystals for detector fabrication.

Simulation and Growth of Cadmium Zinc Telluride from Small Seeds by the Travelling Heater Method

Author : Jordan Douglas Roszmann
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Simulation and Growth of Cadmium Zinc Telluride from Small Seeds by the Travelling Heater Method by : Jordan Douglas Roszmann

Download or read book Simulation and Growth of Cadmium Zinc Telluride from Small Seeds by the Travelling Heater Method written by Jordan Douglas Roszmann and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The semiconducting compounds CdTe and CdZnTe have important applications in high-energy radiation detectors and as substrates for infrared devices. The materials offer large band gaps, high resistivity, and excellent charge transport properties; however all of these properties rely on very precise control of the material composition. Growing bulk crystals by the travelling heater method (THM) offers excellent compositional control and fewer defects compared to gradient freezing, but it is also much slower and more expensive. A particular challenge is the current need to grow new crystals onto existing seeds of similar size and quality. Simulations and experiments are used in this work to investigate the feasibility of growing these materials by THM without the use of large seed crystals. A new fixed-grid, multiphase finite element model was developed based on the level set method and used to calculate the mass transport regime and interface shapes inside the growth ampoule. The diffusivity of CdTe in liquid tellurium was measured through dissolution experiments, which also served to validate the model. Simulations of tapered THM growth find conditions similar to untapered growth with interface shapes that are sensitive to strong thermosolutal convection. Favourable growth conditions are achievable only if convection can be controlled. In preliminary experiments, tapered GaSb crystals were successfully grown by THM and large CdTe grains were produced by gradient freezing. Beginning with this seed material, 25 mm diameter CdTe and CdZnTe crystals were grown on 10 mm diameter seeds, and 65 mm diameter CdTe on 25 mm seeds. Unseeded THM growth was also investigated, as well as ampoule rotation and a range of thermal conditions and ampoule surface coatings. Outward growth beyond one or two centimeters was achieved only at small diameters and included secondary grains and twin defects; however, limited outward growth of larger seeds and agreement between experimental and numerical results suggest that tapered growth may be achievable in the future. This would require active temperature control at the base of the crystal and reduction of convection through thermal design or by rotation of the ampoule or applied magnetic fields.

Optimization of Cadmium Zinc Telluride Crystal Growth for Room Temperature Radiation Detectors

Author : Kelly Allan Jones
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (911 download)

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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:

Development of Traveling Heater Method to Grow Cadmium Telluride (CdTe)/Cadmium Zinc Telluride (CZT) Crystals

Author : Manchanahalli S. Rohan Rao
Publisher :
ISBN 13 :
Total Pages : 56 pages
Book Rating : 4.:/5 (796 download)

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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:

Global Modeling of Bulk Crystal Growth of Cadmium Zinc Telluride in Industrial VB/VGF Systems

Author : Arun Pandy
Publisher :
ISBN 13 :
Total Pages : 762 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Global Modeling of Bulk Crystal Growth of Cadmium Zinc Telluride in Industrial VB/VGF Systems by : Arun Pandy

Download or read book Global Modeling of Bulk Crystal Growth of Cadmium Zinc Telluride in Industrial VB/VGF Systems written by Arun Pandy and published by . This book was released on 2004 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Modeling and Control of Cadmium Zinc Telluride Grown Via an Electro-dynamic Gradient Freeze Furnace

Author : Lisa San Lun
Publisher :
ISBN 13 :
Total Pages : 488 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Modeling and Control of Cadmium Zinc Telluride Grown Via an Electro-dynamic Gradient Freeze Furnace by : Lisa San Lun

Download or read book Modeling and Control of Cadmium Zinc Telluride Grown Via an Electro-dynamic Gradient Freeze Furnace written by Lisa San Lun and published by . This book was released on 2007 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Material Properties of Large-volume Cadmium Zinc Telluride Crystals and Their Relationship to Nuclear Detector Performance

Author :
Publisher :
ISBN 13 :
Total Pages : 9 pages
Book Rating : 4.:/5 (684 download)

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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.

Photoluminescence Characterization of Cadmium Zinc Telluride

Author : Mohamed Alshal
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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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.

CHARACTERIZATION OF CADMIUM-ZINC TELLURIDE CRYSTALS GROWN BY 'CONTACTLESS' PVT USING SYNCHROTRON WHITE BEAM... NASA

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (88 download)

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Book Synopsis CHARACTERIZATION OF CADMIUM-ZINC TELLURIDE CRYSTALS GROWN BY 'CONTACTLESS' PVT USING SYNCHROTRON WHITE BEAM... NASA by :

Download or read book CHARACTERIZATION OF CADMIUM-ZINC TELLURIDE CRYSTALS GROWN BY 'CONTACTLESS' PVT USING SYNCHROTRON WHITE BEAM... NASA written by and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Structural Properties of Cadmium Zinc Telluride and Their Effects on Nuclear Radiation Detector Performance

Author : Hojun Yoon
Publisher :
ISBN 13 :
Total Pages : 288 pages
Book Rating : 4.:/5 (429 download)

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Book Synopsis Structural Properties of Cadmium Zinc Telluride and Their Effects on Nuclear Radiation Detector Performance by : Hojun Yoon

Download or read book Structural Properties of Cadmium Zinc Telluride and Their Effects on Nuclear Radiation Detector Performance written by Hojun Yoon and published by . This book was released on 1998 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Characterization of Cadmium-zinc Telluride Crystals Grown by 'contactless' PVT Using Synchrotron White Beam Topography

Author : Witold Palosz
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.:/5 (131 download)

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Book Synopsis Characterization of Cadmium-zinc Telluride Crystals Grown by 'contactless' PVT Using Synchrotron White Beam Topography by : Witold Palosz

Download or read book Characterization of Cadmium-zinc Telluride Crystals Grown by 'contactless' PVT Using Synchrotron White Beam Topography written by Witold Palosz and published by . This book was released on 1997 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

GROWTH OF CADMIUM-ZINC TELLURIDE CRYSTALS BY CONTROLLED SEEDING CONTRACTLESS PHYSICAL VAPOR TRANSPORT... NASA-CR-204728... SEP. 18, 1997

Author : United States. National Aeronautics and Space Administration
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (226 download)

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Book Synopsis GROWTH OF CADMIUM-ZINC TELLURIDE CRYSTALS BY CONTROLLED SEEDING CONTRACTLESS PHYSICAL VAPOR TRANSPORT... NASA-CR-204728... SEP. 18, 1997 by : United States. National Aeronautics and Space Administration

Download or read book GROWTH OF CADMIUM-ZINC TELLURIDE CRYSTALS BY CONTROLLED SEEDING CONTRACTLESS PHYSICAL VAPOR TRANSPORT... NASA-CR-204728... SEP. 18, 1997 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1998* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: