PARASITIC EFFECTS OF BUFFER DESIGN ON STATIC AND DYNAMIC PARAMETERS OF ALGAN/GAN HIGH ELECTRON MOBILITY TRANSISTORS

GaN-based HEMTs are excellent candidates for next-generation high-power microwave applications. Nevertheless, due to the spontaneous n-type conductivity of GaN crystals, devices equipped with unintentionally-doped buffer experience detrimental short-channel effects, undermining both the device performances and their long-term stability. Technological solutions involve the introduction of carbon and/or iron compensating species which compensate the unintentional donor species, render the GaN buffer layer semi-insulating, and improve the confinement of electrons in the 2DEG. Nevertheless, the presence of foreign impurities and the related peculiar growth conditions, may give rise to enhanced crystallographic defect density. Within this work, we comprehensively investigate the static and dynamic parasitic effects related to the GaN-buffer design, and we discuss the implications on the rf performance and reliability.