Group III-nitride semiconductor technology for discrete transistors and MMICs has a wide range of applications for cell phones, wireless infrastructure (base stations), switching power supplies, and in high performance military electronics. Most of these applications are related to power amplification, but group III-nitrides having much higher breakdown voltages than other compound semiconductors like GaAs or InP also offer significant advantages for toughened, low noise receivers. Low dislocation density GaN films are also a necessity for long-lived blue and UV semiconductor lasers, and a more robust and cost efficient GaN template technology will directly impact the viability of solid state lighting. The proposed work is in direct response to the call in subtopic O1.07 in the 2009 NASA SBIR solicitation for "High-efficiency (> 60%) Solid-State Power Amplifiers (SSPAs), of both medium output power (10 W-50 W) and high-output power (150 W-1 KW), using power combining techniques and/or wide band-gap semiconductor devices at X-band (8.4 GHz) and Ka-band (26 GHz, 32 GHz and 38GHz)" and "Epitaxial GaN films with threading dislocations less than 106 per cm2 for use in space qualified wide band-gap semiconductor devices at X- and Ka-band." These calls for technical advancement are in turn directly related to high data rate communications with future NASA missions to the moon, to Mars, and to the outer solar system.