Microwave noise performances of AlGaN/GaN HEMTs on semi-insulating 6H-SiC substrates

High-performance, low-noise AlGaN/GaN high electron mobility transistors (HEMTs) with 0.25 (mu)m gate-length have been fabricated on semi-insulating 6H-SiC substrates. The devices exhibited a unity current gain cutoff frequency (f/sub T/) of 52.3 GHz, and maximum frequency of oscillation (f/sub MAX/) of 112 GHz. At 10 GHz, a minimum noise figure (NF/sub min/) of 0.75 dB and an associated gain (G/sub a/) of 10.84 dB was obtained when biased at V/sub DS/=10 V and I/sub DS/=40.6 mA/mm. The corresponding values were 1.15 and 7.49 dB at 18 GHz. These results are the first reported microwave noise characteristics obtained from 0.25 (mu)m gate-length GaN HEMTs on 6H-SiC substrates. The use of 6HSiC substrates provides an alternative solution to the full commercialisation of GaN-based technologies for low-noise and high-power electronics.