The commercialization of III-nitride technology and fabrication of high quality GaN based devices has been made possible due to the advances in the deposition of III-N thin-films on Si substrates. AlGaN/GaN high electron mobility transistors (HEMTs) for high power RF applications are predominantly fabricated on either Silicon (Si) or Silicon Carbide (SiC) substrates due to the lack of native GaN substrates. The choice of the substrate is crucial and determines a wide variety of essential material properties, which in turn impact resulting device performance and reliability. Nitronex has adopted 100-mm Si as the substrate of choice; uniform substrates of high quality are affordable and plentiful due to decades of use in the microelectronics industry. The capability of Nitronex’s GaN HEMT epi wafer technology is attributed to the development of novel transition layers that accommodate the stresses originating from the differences in properties of Si substrates and GaN-based materials. These transition layers result in smooth epitaxial films that are free from micropipes and other substrate imperfections which reduce performance, reliability and yield. The resulting GaN-on-Si device technology offers; (a) high power performance at high levels of reliability, (b) is ideally suited for large area RF circuits, (c) is affordable, and (d) is in high volume production today and readily available.