Capitalizing on a potent confluence of expertise in III-Nitride epitaxy, GaN-Si power device designs, and wide-bandgap power electronics, researchers at GeneSiC Semiconductor and Cornell University jointly propose a SBIR program focused on the development of 15 kW/300°C-rated power converters using AlGaN/GaN-Si MOS-HFETs and Schottky rectifiers. The proposed AlGaN/GaN-Si power converters to be developed in this program will usher in a new generation of high-efficiency, low-cost, and radiation-hard power conversion units on-board future NASA spacecraft. Phase I of this proposed work will focus on the optimization of the design and fabrication of the AlGaN/GaN-Si MOS-HFET and NSJ SBR devices. Phase II will be focused on the design and integration of Si/GaN gate-drive circuitry with the power SBRs and transistors to create high-power integrated circuits. Another major objective during Phase II will be the construction of Rad-Hard packaging for the power ICs. At the end of Phase II of this program, a fully-functional 15 kW/300°C rated power converter IC equipped with AlGaN/GaN-on-Si MOS-HFETs, Natural SuperJunction (NSJ) SBRs as free-wheeling diodes and on-chip SiC or III-Nitride gate drive circuitry will be demonstrated at a switching frequency of ≥ 1 MHz and at a temperature of ≥ 300°C. As compared to the existing state-of-the-art power electronics technology, the proposed AlGaN/GaN-on-Si power converters will offer (A) Lower on-state losses, 300°C operation and 1 MHz switching capability (B) A Lateral device architecture, which is highly desirable for construction for monolithic power integrated circuits (C) Possibility of hybrid interconnection of III-Nitride Power Devices with on-chip Rad-Hard AlGaN/GaN Gate Drive Circuitry (D) Desirable Normally-OFF Power Switches.