A High RF-Performance AlGaN/GaN HEMT With Ultrathin Barrier and Stressor In Situ SiN

The submicrometer gate HEMT is fabricated with an ultrathin-barrier (UTB) AlGaN/gallium nitride (GaN) combined with in situ SiN passivation. The sheet resistance of the UTB Al0.2Ga0.8N (4 nm)/GaN heterostructure is effectively reduced by the SiNx passivation layer grown by metal organic chemical vapor deposition (MOCVD), from 6500 to 312 Omega/square. With the 20-nm stress-engineered in situ SiN, the device not only provides a large output current of 1.05 A/mm but also demonstrates promising potential on the RF applications, which gives AlGaN material two records high cutoff frequency f(T)/f(max) of 157 GHz/334 GHz for 100-nm gated device and 211 GHz/379 GHz for 70-nm gated device. During the continuous wave (CW) power measurement at 30 GHz, the 70-nm devices exhibit a large output power of 4.6 W/mm associated with a peak poweradded efficiency (PAE) of 48.1% and a gain of 11.6 dB (V-ds = 20 V), and a high PAE of 53.8% with an output power density of 1.9 W/mm and a gain of 10.8 dB (V-ds = 10 V), respectively. The huge potential of the UTB-AlGaN/GaN is demonstrated for high- frequency and large-output power applicationswhen it is combined with the in situ SiN, which is necessary for future communication systems.

Automated summary

The study successfully fabricated submicrometer gate HEMT devices with optimized UTB AlGaN/GaN heterostructures through SiN passivation, showing great potential in both RF applications and power performance.