Unpassivated AlGaN/GaN HEMTs with CW Power Density of 32.2W/mm at 25GHz Grown by Plasma-Assisted MBE

The Ka band power performance of unpassivated AlGaN/GaN HEMTs grown by plasma-assisted molecular beam epitaxy on 6H-SiC substrates is reported. Transistors with a gate length of 0.2mm, source-drain spacing of 2mm, and 100mm periphery displayed maximum drain currents greater than 1.6A/mm. Small signal S-parameter measurements yielded an f sub T of 53GHz and f sub max of 109GHz. Passive load pull measurements at 25GHz of 0.2mm x 100mm transistors yielded a power density of 3.2W/mm with 30% PAE and 44% drain efficiency at 1.8dB gain compression. To the best of our knowledge, this is the first report of RF output power above 20GHz from MBE grown AlGaN/GaN HEMTs.