New Spectrometry Crystals
CdZnTe Crystalls for Recording and Spectrometry of Nuclear Radiation
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
- MAT-ELE/Organic and Electronics Materials/Materials
3 Approved without Funding
Research Institute of Scientific Instruments, Russia, Moscow reg., Lytkarino
- Russian Academy of Sciences / Institute of Crystallography, Russia, Moscow
- CENTRE NATIONAL DE LA RECHERSHE SCIENTIFIQUE, France, Meudon\nInstitut fur Kristallzuchtung, Germany, Berlin
Project summaryThe present project is directed at development of the growth technology of large, homogeneous, high-ohmic monocrystals of quasi-binary Cd1-xZnxTe compounds for manufacturing nuclear radiation detectors, operating at room temperature.
The given compound, at х=0.1–0.15, has particular advantages over the most known broad-zone detecting materials. At identical efficiency of gamma-quantums recording, this material has a resistance by an order of magnitude greater and, accordingly, the lower currents of leakage, than cadmium telluride crystalls and at the same time has a mobility of charge carriers greater by several fold than mercury di-iodide crystalls.
The project includes development of a reproduced growing procedure for monocrystals of broad-zone binary compounds from a gas phase, development and creation of a pilot sample of a semi-commercial installation for growing.
For deriving crystalls, a method of vapor deposition of source's binary compounds on an oriented substrate is used. The elimination of spontaneous nucleation and growth of a polycrystal are achieved by selective cooling of a crystall in respect to environmental details of a crystallizer with the use of a light guide. For preventing crystallization on side walls and accretion of the crystall with details of the crystallizer, the evaporation of a crystalline material from a lateral area of the crystall and from walls of the growth chamber through a gap between ends of the light guide and edges of the growth chamber with temperature gradient under the diffusion mode of vapor transport is provided.
At the first stage, theoretical and experimental studying the growth process of Cd1-xZnxTe monocrystal (KST) of a preset composition from a gas phase is carried out.
The growth experiments and development of physical and mathematical model of the process is supposed to carry out with the purpose of determination of its optimum modes and requirements for a construction of the growing installation.
The next stage is making and putting into operation of a prototype installation for deriving KST monocrystals of the “detecting “ quality. It includes also conducting numerous growth and measuring experiments allowing to correct technological modes with «output » of the most perfect samples by structural and physical properties.
At the third, terminating, stage, adjusting of modes and construction of the growth installation by results of the previous experiments are performed.
The engineering specifications for the pilot installation are drawn up. On the basis of the obtained crystalls, detecting structures are made, and study of their radiometric and spectrometer parameters are carried out. According to an assessment of the Project’s authors grounded on the available works, implementation of the project will allow:
1. To complete a procedure for the reproduced growth of large homogeneous perfect crystalls from a gas phase which would be suitable for manufacture of nuclear radiation detectors on their basis. The expected parameters of the crystalls: a diameter of ~50 cm and resistivity of 109 ohm×cm.
2. To develop, make and put into operation 2 installations for the KST crystall growth from a gas phase. To prepare a request for development of the design documentation for duplicating the given installation.
3. To carry out an estimate of radiometric and spectrometric parameters of the grown crystals at recording nuclear radiations of different types.
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