High-efficiency GaN HEMTs on 3-inch semi-insulating SiC substrates

Abstract

We report on device performance and reliability of our 3″ GaN high electron mobility transistor (HEMT) technology. A1GaN/GaN HEMT structures are grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition (MOCVD) with sheet resistance uniformities better than 2%. Device fabrication is performed using standard processing techniques involving both e-beam and stepper lithography. A1GaN/GaN HEMTs demonstrate excellent high-voltage stability and large efficiencies. Devices with 0.5 μm gate length exhibit two-terminal gate-drain breakdown voltages in excess of 160 V and drain currents well below 1 mA/mm when biased at 80 V drain bias under pinch-off conditions. Load-pull measurements at 2 GHz return both a linear relationship between drain bias voltage and output power as well as power added efficiencies beyond 55% up to 72 V drain bias for which is obtained. Reliability tests indicate a promising device stability under both radio frequency (RF) and direct current (DC) stress conditions. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.