PROJECTION TV AND LASER MATERIALS

Rosich and Co., Moscow, manufactures EBSL projection tubes. The lasing material is a wafer of single crystal II-VI compound that has been polished to a thickness of about 30 microns. The company had a well-equipped polishing and characterization facility at Chromatron. Rosich has a research program investigating the possibility of using MOCVD epitaxial material. The company's scientists have grown ZnSe on GaAs which achieved lasing at room temperature with an output of 2.5 W, 3-4% efficient, in deep blue. They stated that when they used conventional MOCVD techniques, they were unable to achieve lasing. The maximum size of the lasing material that they were able to grow was 15 cm2. They made proprietary changes in processing and growth to attain lasing. They foresaw a difficulty in producing MOCVD grown layers for other colors because of the lack of a suitable substrate. The Department of Optoelectronics, Institute of Semiconductors, Ukraine Academy of Sciences, develops materials for projection TV screens. Each element of the screen is composed of a small crystal that serves as a laser source.

Platan manufactures quantoscopes, which are solid-state e-beam pumped lasers. The company obtains RGB with CdSe for green, CdSe + CdS for red, and Cd:ZnSe for blue. The Zelenograd complex has expertise in crystal growth from the gas phase by the Davidov- Markova method. There is a large, well-equipped crystal growth facility for the preparation and characterization of II-VI crystals for screen fabrication. Screen processing and characterization facilities include lapping and polishing equipment, and cathodoluminescence and photoluminescence testing stations. The crystal growth reactors consist of closed upright silica tubes containing a basket-like structure to hold the polycrystalline starting material above a pedestal upon which the flat seed plate is placed. The furnace is lowered over the tube and the assembly is heated to approx. 900-1,000 degrees centigrade. The growth rate is about 10 mm/min. The crystal compositions grown include CdSxSe1-x for the green and red screens, and CdxZn1-xSe for the blue screens. The yield for 3-inch diameter CdSe crystals was about 20%. Platan has a complete crystal evaluation laboratory that includes X-ray diffraction, rocking curves, SEM, TEM, and photoluminescence.

The V.M. Glushkov Institute of Cybernetics at the Academy of Sciences of Ukraine conducts high-speed, high-data rate laser research, which includes development of new materials with gallium-arsenide and indium-gallium-arsenide, development of lasers up to 10 GHz, and improvement of optical fiber and fiber- optic systems.


Published: December 1994; WTEC Hyper-Librarian