AlGaN/InGaN HEMTs for RF current collapse suppression

A report is made on the DC, RF and large-signal pulsed characteristics of unpassivated AlGaN/InGaN/GaN high electronmobility transistors (HEMTs) grown by molecular beam epitaxy on sapphire substrates. The devices with a 0.5 (mu)m gate-length exhibited relatively flat transconductance (g/sub m/) with a maximum drain current of 880 mA/mm, a peak g/sub m/ of 156 mS/mm, an f/sub T/ of 17.3 GHz, and an f/sub MAX/ of 28.7 GHz. In addition to promising DC and RF results, pulsed I-V measurements reveal that there is little current collapse in the AlGaN/InGaN HEMTs. These results indicate that the output power of InGaN channel HEMTs should not be limited by surface-state-related current collapse. A