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RESEARCH AND DEVELOPMENT ON HIGH PURITY SILICON CARBIDE CRYSTALS, SIC JUNCTIONS AND SIC ACTIVE DEVICES
TRANS WORLD AIRLINES INC KANSAS CITY MO
By growing epitaxial layers of silicon carbide from the vapor phase onto single crystal platelets, P-N junctions were produced with reverse breakdown voltages up to 400 volts throughout the temperature range from 25 to 500 C. A closed graphite crucible provided the environment for evaporation for silicon carbide and condensation of the vapor on the cooler hexagonal crystal platelet. Generally, the grown epitaxial layers were hexagonal although, cubic deposits can be formed by proper choice of temperature and pressure variables. The intrinsic silicon carbide layers are transparent, pure, and possess a high resistivity. They are formed by the sublimation of a very pure silicon carbide charge. By the use of an aluminum doped charge, P-type layers were deposited which were overdoped by the introduction of nitrogen during the growth process. In this way, P-N junctions were formed with satisfactory reverse breakdown characteristics. The high resistivity of the substrate platelets, however, prevented diodes from showing attractive forward characteristics. Author
AF19 604 4989