Microwave GaN MESFET on Conducting SiC Substrates

We will develop and demonstrate high power GaN HDMESFETs grown over conducting 6H-SiC substrates for effective thermal management. The SiC substrate will be separated from the device channel by insulating GaN buffer layer thick enough to have thecapacitance between the substrate and the device contact pads smaller then or comparable to the gate-to-channel capacitance (patent pending). This will allow us to control noise, minimize backgating, sidegating, and current slump. Also, this substratecontact can be used to adjust the device threshold voltage, similar to what is done in silicon MOSFETs.A successful Phase II program will yield transistors to be used in MMIC modules for fabrication of highly efficient X-band power amplifiers. These havedirect applications in several commercial and military systems such as radars and wireless communication systems operating in 2-10 GHz frequency range. Primarily due to the significantly lower cost of conducting SiC substrates , transition from insulating4H-SiC to conducting 6H-SiC substrate material would significantly reduce the cost of the microwave power devices.