Research and Development on Advanced Silicon Carbide Thin Film Growth Techniques and Fabrication of High Power and Microwave Frequency Silicon Carbide-Based Device Structures
Annual letter rept. for FY1990
NORTH CAROLINA STATE UNIV AT RALEIGH
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The RF operation of MESFETs and bipolar transistors fabricated from both alpha - and beta-SiC have been modeled. The results show that SiC has considerable promise for producing microwave power MESFETs with RF output power capability greater approx. 4 times than can be obtained with any of the commonly used semiconductors e.g., GaAs. this due to the high breakdown field of SiC that allows high bias voltage to be applied. These device modeling efforts have been used as a guide to design a new MESFET mask set with a aS micron gate length and reduced gate pad area. For the first time, positive gain was observed for a SiC transistor at microwave frequencies. The highest values for Ft and Fmax were 2.9 GHz and 1.9 GHz, respectively. The highest current and power gains observed at 1.0 GHz were 8.5 dB and 7 db, respectively. Avalanche characteristics for a 6H-SiC IMPATT were observed for the first time. Heteroepitaxial growth of Ti on 0001 6H-SiC has been achieved at room and elevated temperatures. Current voltage measurements display shifts toward ohmic behavior after annealing at 400 C. Molecular beam epitaxy equipment has been designed and commissioned.
- Inorganic Chemistry