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

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 fabri- cation have been made, the quality and reproducibility of epitaxial structures de- posited on mismatched substrates re- mains a key factor limiting device per- formance. We have fabricated AlGaN HEMTs using structures deposited on sapphire and high resistivity SiC sub- strates in various MOCVD systems with distinct cross wafer uniformity traits. The resulting device DC and small signal RF characteristics show a strong correla- tion to cross wafer trends measured prior to processing using a range of nonde- structive physical and electrical tech- niques. These provide an approach for rapid and effective characterization of AlGaN HEMT material that can be imple- mented prior to device processing, and provide predictive information on com- pleted device performance.