N-Polar GaN HEMT Technology for mm-Wave Amplifiers using Commercial 4-inch Wafer Process Facilities

This paper describes N-polar GaN HEMT technology for 28GHz mm-wave amplifiers of 10W class. High-power, high-efficiency mm-wave amplifiers are key devices for 5G and 6G wireless communication systems. We demonstrated innovative high-k MIS N-polar GaN HEMTs which were fabricated, for the first time, using commercial 4-inch wafer process facilities. The device design including an N-polar epi-structure have been redesigned for amplifier’s operations, and developed N-polar GaN HEMT implemented unique HfSiOx gate insulating film, which achieved an extremely low gate leakage current and a slight threshold-voltage-shift after applying an operational bias stress. Moreover, we compared many types of devices including N-polar GaN HEMTs in terms of output-power-characteristics, linearity, and high-frequency performance. We will show our physical perspectives of GaN-related high-power devices and mm-wave power amplifiers.