Beta-Silicon Carbide has been known for many years to have excellent theoretical properties for the production of high power microwave devices. The combination of its wide bandgap, high saturated electron drift velocity, high breakdown electric field, low dielectric constant and high thermal conductivity give it a figure of merit for high power microwave applications that is 1100 times better than that of silicon and 183 times better than that of gallium arsenide. The primary advantage of beta silicon carbide is higher carrier mobility which, for electrons, has been measured and calculated to be high. Another advantage junction power devices is the lower junction barrier because of the smaller bandgap. Also the resistance for contacts developed to date are lower for 3 cubic structures than for 6 hexagonal structures. Thus, the beta-form is more desirable for high frequency, high power applications. However, a process for growing high quality boules of beta- silicon carbide from which to fabricate wafers and devices has not been developed. It is proposed to evaluate two different approaches for growth of beta-silicon carbide single crystal boules during Phase I. Further development of the most promising process will be the primary Phase II objective.
