High-power gan-hemt with low current collapse for millimeter-wave amplifier

Abstract

There are high expectations for GaN high electron mobility transistors (GaN-HEMT) to serve as a key device in the production of a high power and high efficiency millimeter-wave amplifier. Until now, an extremely low three-terminal pinched-off-current of less than 10-6 A/mm was achieved by applying band engineering. It improved the on-state breakdown voltage to 50 V and the off-state breakdown voltage to over 100 V (Makiyama et al., Phys. Status Solidi C 6(S2), S1012 (2009) [1]). However, the output power of a GaN-HEMT decreases due to current collapse. In particular, the influence of current collapse increases in a GaN-HEMT with a short gate-length. In this work, technology was developed to reduce this amount of current collapse. By utilizing thin silicon nitride passivation film that contained many Si-H bonds, the current collapse was remarkably improved. A 3-stage common source amplifier MMIC was fabricated that used the current collapse reducing technology. The Pin vs. Pout characteristics were measured at the W-band. Excellent power characteristics, such as Pout of 1.3 W at 75 GHz at 35 V operation, and a frequency bandwidth of 13 GHz were demonstrated. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.