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Sapphire Substrates for Micro- and OptoelectronicsDetails
Horizontal Directed Solidification Method
The Horizontal Directed Solidification Method (HDSM) allows to grow the sapphire of any crystallographic orientation in the form of plates with record size (350x500x40 mm3), inaccessible to other growth methods.
“Gorizont-3”plants fleet for sapphire crystal obtaining by HDSM:
Institute for Single Crystals of NAS of Ukraine developed advanced technology for sapphire crystals growing by HDSM in the protective gas atmospheres, which has several advantages over the well-known vacuum technology (Bagdasarov method). Improved technology has also been successfully used for growing of scintillation crystals of rare earth aluminum garnets (LuAG:Pr, LuAG:Ce, YAG:Ce).
HDSM has several significant advantages compared with other melt method:
• it is possible to grow sapphire crystals in the form of plates of size, which are inaccessible by other methods;
• it is a highly effective method that allows to obtain crystals of optical quality (1, 2 and 3 categories);
• provides an opportunity to use available materials for making the temperature field and manufacturing of containers of various geometrical shapes;
• seeding and crystallization process can be monitored visually or with optical devices;
• an effective evaporation of impurities (the grown crystals have high chemical purity of 99.996%) takes place due to the large area of the melt;
• allows to grow crystals with low (<2 kg/mm2) residual voltage, which makes it possible in some cases to exclude special technical annealing.
Advanced growth technology and correcting annealing allow to obtain UV-resistant material.
|Transmission spectrum of sapphire|