High efficiency and low leakage AlGaN/GaN HEMTs for a robust, reproducible and reliable X-band MMIC space technology

We report on epitaxial growth, processing, device performance and reliability of our GaN HEMT and MMIC technology on 3-inch SiC substrates. Processing is performed in MSL technology consisting of frontside processing (0.25 µm gate length and complete passive matching network), substrate thinning to 100 µm, and backside processing including front-to-back substrate via holes. The process technology exhibits excellent unifor-mity across a single wafer as well as high reproducibility from wafer to wafer. HEMTs have high PAE (50% without intentional harmonic matching) and low leakage currents (below 100 µA/mm at a drain bias as high as 150 V). We have fabricated one-stage and two-stage MMICs with efficiencies beyond 40%. The reliability of our MMIC technology is investigated using one-stage MMICs under RF operation at 30 V showing a drift of around 0.3 dB in output power over 1000 h of operation at a Raman calibrated channel temperature of 185°C