5.4.8 Technology H: AlGaN/GaN HEMTs

Al$_x$Ga$_{1-x}$N/GaN based HEMT structures are shown for experimental comparison. The layers are based on a MOCVD growth process on sapphire substrates with a gate length down to ${\it l}_{\mathrm{g}}$= 200 nm. Typical Al concentrations are $x$= 0.25 in the barrier. In contrast to Fig. 3.1 single heterojunction devices are processed.