9. Better GaN HEMTs for High-Power Amplifiers
Category: Power Devices
Paper 9.1, Collapse-Free High Power InAlGaN/GaN-HEMT with 3 W/mm at 96 GHz; K. Makiyama et al, Fujitsu/Tokyo Institute of Technology
High electron-mobility transistors (HEMTs) made from GaN have great potential for use in high-power millimeter-wave amplifiers for high-data-rate wireless networks. Normally these transistors use an InAlN barrier layer to separate the channel from the source and drain. However, a team led by Fujitsu will show that InAlN is inadequate for devices intended for use in high-power amplifier applications because it facilitates “current collapse,” where a collection of electron traps occurs and alters the device’s performance. Instead, they used a higher-quality barrier material, InAlGaN. They also employed a novel double-layer SiN passivation technique. The 80nm-channel-length InAlGaN/GaN power HEMTs they built demonstrated a record 3 W/mm output power density at 96 GHz, which is a 60% improvement over the best results reported to date. Reliability also was superb. The power and reliability performance put the HEMTs at the state-of-the-art for use in W-band amplifiers (75–110 GHz).