Zinc and Cadmium Chalcogenides
Development of the Environmentally Safe Manufacture Technology of Crystalline Materials Based on Zinc and Cadmium Chalcogenides for IR Opto-electronics
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
8 Project completed
Senior Project Manager
Lapidus O V
Vavilov State Optical Institute (GOI), Russia, St Petersburg
- SOREM , France, Uzés\nInstitut de Chimie de la Matière Condensée de Bordeaux, France, Pessac\nCrystal GmbH, Germany, Berlin\nCEA / DTA / CEREM/CEN Grenoble, France, Grenoble\nVITCON Projectconsult GmbH, Germany, Jena
Project summaryThe given project is the advanced variant of the Project # 638 on basis of results obtained due to financing given on the Grant on development of the Project # 638. In the project it is offered to use scientific and technical potential of Scientific Center "S.I.Vavilov GOI" and its achievements in the field of optical materials for development of environmentally safe manufacture technology of crystalline materials based on chalcogenides of zinc and cadmium for use in IR optoelectronic devices and in particular:
- in medical diagnostic thermovision devices,
- in navigating devices suitable for operation in conditions of bad visibility,
- at IR-geodetic measurements,
- in devices of ecological monitoring, optical gas-analyzers,
- in thermovisors used at fish- and geological prospecting,
- in thermovisors used for detection of heat losses in buildings,
- in thermovisors used to search latent (for example, underground) fires, and also for fire-prevention protection
- in thermovisors used to detect people in the destroyed premises and remote places.
At present, methods of physical vapour and chemical deposition are used for manufacture of IR materials based on metal chalcogenides (Zinc Sulfide and Selenide). Physical vapour deposition (PVD) method (vacuum sublimation of ZnSe, for example) enables to produce high-transparent optical material but lacking mechanical strength. It is possible to raise the bending strength limit of polycrystalline optical materials by means of reduction of grain size. One way of doing this is to grow ZnSe polycrystalline by method of chemical vapour deposition (CVD). The obtained durability of the optical material is in 1,5 time longer in this case than in the first one. However, this method is extremely dangerous because of the necessity to use toxic gaseous and explosive reagents (Hydrogenselenide, Hydrogensulfide and Hydrogen) as initial products. In order to organize the manufacture of materials by the method of chemical vapour deposition the complex and expensive equipment and special equipment for absorption of toxic gaseous products of reaction is required. Among the known methods there are also the methods of crystallization of metal chalcogenides from solutions in low-melting-point metals or alloys (Tin, Bismuth, and others). Till present these methods were used only for growing of thin epitaxial chalcogenide films. There are no data concerning the obtaining of the chalcogenides polycrystalline layers though it is evident that there can be obtained a material with a very small size of grain hence with a high mechanical strength. The crystallization from a solution in metals allows to growth both monocrystal epitaxial film and metal chalcogenides polycrystalline layers with the very small size of grain hence with high mechanical durability. Furthermore this method allows to obtain a material with high chemical purity by extraction of impurity of all heavy metals from a growing crystal into melt herewith the selective doping of the growing material with one or another additive is possible which appears to be important while developing the semi-conductor devices and Led's on basis of epitaxial structures.
In the given work it is supposed to develop the ecologically safe manufacture technology of Zinc and Cadmium chalcogenide-based crystal materials for IR optoelectronics using methods of crystallization from solutions in metals. This technology does not require utilization of toxic gaseous or explosive initial products and can be realized in closed space without giving off gaseous products and is environmentally safe from this point of view.
It is supposed to investigate in this Project:
- solubility of metal chalcogenides in Tin-based alloys,
- kinetics of chalcogenide crystallization from solution in alloys depending on temperature gradient,
- solubility of metal-solvent in chalcogenide lattice,
- optical and strength features of thick layers of polycrystalline Zinc and Cadmium chalcogenides, semiconductor and luminescent properties of chalcogenide crystalline films grown by crystallization from metal-solvent.
The fundamentals of manufacture technology of polycrystalline fine-grained optical materials transparent in wide spectral range and possessing increased bending strength will be developed on basis of the obtained results. It is expected that crystallization from metal-solvents will allow to simplify considerably the equipment in comparison to the known method of chemical vapor deposition and will ensure manufacture of fine-grained and thereby mechanically stronger material than that produced by physical vapor deposition. The new method will enable to obtain high purity crystalline chalcogenides, to control their properties and will ensure the environmental safety of poly- and monocrystal metal chalcogenide growth. The samples of polycrystalline optical IR materials with increased mechanical resistance strength (up to 40MPa in case of ZnSe) will be obtained as a result of work..