W-band N-polar GaN MISHEMTs with high power and record 27.8% efficiency at 94 GHz

We report on the W-band power performance of N-polar GaN MISHEMTs demonstrating a record power-added efficiency (PAE) of 27.8% while maintaining an excellent output power density of 3 W/mm and 7.4 dB peak gain at 94 GHz. To enable this performance, a novel device technology is presented that utilizes the advantages of the inverted polarization of N-polar GaN to mitigate dispersion and improve access region conductivity through the addition of a 47.5 nm in-situ GaN cap layer. To obtain these results past work has been extended through pad layout optimization and reduction of lateral dimensions.