W-Band Power Performance of SiN-Passivated N-Polar GaN Deep Recess HEMTs
Brian Romanczyk, Xun Zheng, Matthew Guidry, Haoran Li, Nirupam Hatui, Christian Wurm, Athith Krishna, Elaheh Ahmadi, S. Keller, Umesh K. Mishra
Abstract
This letter reports on the improvement of the large-signal W-band power performance of nitrogen-polar gallium nitride deep recess high electron mobility transistors with the addition of a 40-nm-thick ex-situ silicon nitride passivation layer deposited by plasma enhanced chemical vapor deposition. The additional passivation improves the dispersion control allowing the device to be operated at higher voltages. Continuous-wave load pull measurements performed at 94 GHz on a 2×37.5 μm transistor demonstrated an improvement in the peak power-added efficiency (PAE) to 30.2% with an associated output power density of 7.2 W/mm at 20 V drain bias. Furthermore, at 23 V, a new record-high W-band power density of 8.84 W/mm (663 mW) was achieved with an associated PAE of 27.0%.