Production of Large Area Semi-Insulating Gallium Nitride Substrates

Ultra-high performance multi-function RF electronics are required by the United States Department of Defense to enable next generation radar and sensor networks in response to an increasingly diverse array of threats to our military and our homeland. An elegant potential solution is that of gallium nitride (GaN) RF electronics, which has shown great promise on currently available yet foreign substrates such as silicon carbide, which have provided for high-performance GaN FET device demonstrations albeit on highly dislocated epitaxial device layers. However, further advances in both performance and especially reliability, both of which require improved epitaxial device layer quality, are required before system insertion is possible. A cost-effective source of large-diameter, high-quality semi-insulating (SI) GaN substrates offers the potential to revolutionize radar and sensor applications by enabling critical advances in performance and reliability of high-power high-frequency electronics. In the Phase I STTR Kyma Technologies demonstrated the feasibility of producing 3” diameter SI GaN substrates with resistivities of 108 Ohm*cm. The Phase II program will focus on further improvement of process stability and optimization of process variables, in conjunction with computer modeling to improve the quality and process yield for making uniform, high-quality 3” diameter native SI GaN boules and substrates. This development effort will include optimizing the crystal growth for reduced defect density, high electrical resistivity, high thermal conductivity, and the elimination of cracks from the wafers. Crack free 3” diameter SI-GaN substrates will be delivered at the end of Phase II with high thermal conductivity, low defect density, and high electrical resistivity.