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High-efficiency GaN HEMTs on 3-inch semi-insulating SiC substrates

Hocheffiziente GaN Transistoren auf 3-Zoll semi-isolierenden SiC Substraten
: Waltereit, P.; Bronner, W.; Quay, R.; Dammann, M.; Müller, S.; Kiefer, R.; Raynor, B.; Mikulla, M.; Weimann, G.


Physica status solidi. A 205 (2008), No.5, pp.1078-1080
ISSN: 0031-8965
ISSN: 1862-6300
ISSN: 1521-396X
ISSN: 1862-6319
Journal Article
Fraunhofer IAF ()
GaN; HEMT; Transistor; power electronics; Leistungselektronik; reliability; Zuverlässigkeit

We report on device performance and reliability of our 3" GaN high electron mobility transistor (HEMT) technology. AlGaN/GaN HEMT structures are grown on semi-insulating SiC substrates by metal-organic chemical vapor deposition (MOCVD) with sheet resistance uniformities better than 2%. Device fabrication is performed using standard processing techniques involving both e-beam and stepper lithography. AlGaN/GaN HEMTs demonstrate excellent high-voltage stability and large efficiencies. Devices with 0.5 mu m gate length exhibit two-terminal gate-drain breakdown voltages in excess of 160 V and drain currents well below 1 mA/mm when biased at 80 V drain bias under pinch-off conditions. Load-pull measurements at 2 GHz return both a linear relationship between drain bias voltage and output power as well as power added efficiencies beyond 55% up to 72 V drain bias for which an output power density of 9 W/mm with 25 dB linear gain is obtained. Reliability tests indicate a promising device stability under both radio frequency (R-F) and direct current (DC) stress conditions.