Microwave performance of AlGaN/GaN metal insulator semiconductor field effect transistors

Metal-insulator semiconductor field effect transistors (MISFETs) from surface-passivated undoped AlGaN/GaN heterostructures were fabricated on sapphire using a gate-window process that does not severely impact its performance. Measured static output characteristics include full channel currents (I-max) Of roughly 750 mA/mm and peak transconductances (g(m)) of 100-110 mS/mm. With evidence for reduced DC-to-RF dispersion from gate-lag measurements, these devices at 4 GHz with 28.0 V bias generated maximum output power densities of 4.2 W/mm and 36% power added efficiency. The process when applied to 2-inch wafers produced with high yield 0.6-mum MISFETs exhibiting consistent static performance over the whole wafer with a mean I-max value of 754 mA/mm and a mean g(m) value of 66 mS/mm at an impressive standard deviation <5%.