THE POTENTIAL OF DIAMOND AND SIC ELECTRONIC DEVICES FOR MICROWAVE AND MILLIMETER-WAVE POWER APPLICATIONS

There is significant interest in developing microelectronic devices for blue emission, high temperature, high power, high frequency, and radiation hard applications. This interest has generated significant research effort in wide bandgap semiconductor material, in particular SiC and semiconducting diamond. Both of these materials are similar in crystal structure with half of the carbon atoms in the diamond structure replaced by Si to produce SiC. However, the latter material exists in a host of polytypes, the causes of which are not completely understood. The deposition of monocrystalline diamond at or below 1 atm total pressure at T < 1000-degrees-C has been achieved on diamond substrates, although deposited film has been polycrystalline on all other substrates. For significant application to electronic devices, the heteroepitaxy of single crystal films of diamond and an understanding of mechanisms of nucleation and growth, methods of impurity introduction and activation, and further device development must be achieved. The technology of producing SiC is more advanced and the deposition of thin films and the associated technologies of impurity incorporation, etching, and electrical contracts have culminated in a host of solid-state devices. In this paper, the potential of SiC and diamond for producing microwave and millimeter-wave electronic devices is reviewed. Both of these materials have been proposed for fabrication of devices capable of producing RF output power significantly greater than can be achieved with comparable devices fabricated from commonly used semiconductors such as Si and GaAs. Theoretical calculations are presented of the RF performance potential of several candidate high frequency device structures: the MEtal Semiconductor Field-Effect Transistor (MESFET), the IMPact Avalanche Transit-Time (IMPATT) diode, and the Bipolar Junction Transistor (BJT).