Correlation of materials characteristics with microwave device performance in AlGaN high electron mobility transistors

R. L. Messham, H. G. Henry, G. Augustine, M. F. MacMillan
I. Ferguson, D. Gotthold, D. Thomson, R. Davis
G. C. DeSalvo and J. J. Zingaro
Northrop Grumman Electronic Sensors and Systems Sector

AlGaN based high electron mobility transistors offer the promise of 5-10X the power density of similar InP and GaAs based structures coupled with attractive noise figure, at frequencies up to mmWave. Although significant advances in materials deposition and device fabrication have been made, the quality and reproducibility of epitaxial structures deposited on mismatched substrates re-mains a key factor limiting device performance. We have fabricated AlGaN HEMTs using structures deposited on sapphire and high resistivity SiC substrates in various MOCVD systems with distinct cross wafer uniformity traits. The resulting device DC and small signal RF characteristics show a strong correlation to cross wafer trends measured prior to processing using a range of nondestructive physical and electrical techniques. These provide an approach for rapid and effective characterization of AlGaN HEMT material that can be implemented prior to device processing, and provide predictive information on completed device performance.