The thermal degradation behaviour of AlGaN/GaN HFETs with advanced source/d
rain and gate metallisations is reported. Using electrical and XRD measurem
ents, it is demonstrated that HFETs with barrier-containing Ti/Al/Ti/Au/WSi
N ohmic and the Ir/Au Schottky contacts are stable during aging at 500 degr
ees C up to 120h.