Material and device issues of GaN-based HEMTs

Material structure and device processing issues related to the performance of high-frequency and high-power AlGaN-GaN HEMTs are discussed. Results on selected issues like transport properties of highly resistive buffer layers, persistent photoconductivity in 2DEG structures, preparation and properties of ohmic and Schottky-barrier contacts and HEMT devices, as well as analysis of deep traps in HEMTs are addressed in this paper in detail.