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 Al 0. 2 Ga 0. 8 N (4 nm) /GaN heterostructure is effectively reduced by the SiN x passivation layer grown by metal organic chemical vapor deposition (MOCVD), from 6500 to 312~ /⬜. 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 ₓ/f ₌₀ₗ 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 power-added efficiency (PAE) of 48. 1% and a gain of 11. 6 dB (V ₃ₒ =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 ₃ₒ =10 V), respectively. The huge potential of the UTB-AlGaN/GaN is demonstrated for high-frequency and large-output power applications when it is combined with the in situ SiN, which is necessary for future communication systems.