LARGE BETA-SILICON CARBIDE SINGLE CRYSTALS BY VACUUM LIQUID PHASE EPITAXY

WIDE-BANDGAP SEMICONDUCTORS SUCH AS BETA-SILICON CARBIDE (BETA-SIC) HAVE THE POTENTIAL TO BE USEFUL IN THE FABRICATION OF ELECTRONIC DEVICES THAT CAN OPERATE AT HIGH TEMPERATURES AND HIGH POWER LEVELS IN CORROSIVE ENVIRONMENTS. SUCH DEVICES CURRENTLY UNDER CONSIDERATION INCLUDE MESFET, IMPATT DIODE, AND BIPOLAR TRANSISTORS. THESE DEVICES ARE COMMONLY FABRICATED FROM SILICON OR GALLIUM ARSENIDE AND ARE USED AT MICROWAVE AND MILLIMETER-WAVE FREQUENCIES. THE RESULTS OF SIMULATIONS INDICATE THAT BETA-SIC HAS CONSIDERABLE PROMISE FOR USE IN MICROWAVE-POWER MESFETS, WITH AN RF OUTPUT POWER CAPABILITY GREATER THAN CAN BE OBTAINED WITH ANY OF THE COMMONLY USED SEMICONDUCTORS. A PROPERLY DESIGNED AND FABRICATED BETA-SIC MESFET IS CAPABLE OF PRODUCING ABOUT FOUR TIMES THE MICROWAVE RF OUTPUT POWER CAPABILITY OF A COMPARABLE GAAS MESFET. CHEMICAL VAPOR DEPOSITION (CVD) AND MOLECULAR BEAM EPITAXY (MBE) TECHNIQUES HAVE BEEN PRIMARILY USED AS THE METHOD FOR GROWTH OF BETA-SIC. NEITHER OF THESE PROCESSES, HOWEVER, LENDS ITSELF TO THE ECONOMICAL PRODUCTION OF LARGE SINGLE CRYSTALS FROM WHICH WAFERS CAN BE OBTAINED. ULTRAMET PROPOSES TO UTILIZE VACUUM LIQUID PHASE EPITAXY (VLPE) TO GROW BETA-SIC.