Field plated 0.15 mu m GaN HEMTs for millimeter-wave application

SiN dielectrically-defined 0.15 mu m field plated GaN HEMTs for millimeter-wave application have been presented. The AlGaN/GaN hetero-structure epitaxial material for HEMTs fabrication was grown on a 3-inch SiC substrate with an Fe doped GaN buffer layer by metal-organic chemical deposition. Electron beam lithography was used to define both the gate footprint and the cap of the gate with an integrated field plate. Gate recessing was performed to control the threshold voltage of the devices. The fabricated GaN HEMTs exhibited a unit current gain cut-off frequency of 39 GHz and a maximum frequency of oscillation of 63 GHz. Load-pull measurements carried out at 35 GHz showed a power density of 4 W/mm with associated power gain and power added efficiency of 5.3 dB and 35% respectively for a 0.15 mm gate width device operated at a 24 V drain bias. The developed 0.15 mu m gate length GaN HEMT technology is suitable for Ka band applications and is ready for millimeter-wave power MMICs development.