Research and Development of GaN-Based HEMTs for mm-Wave and THz Wireless Communications

GaN-based transistors and amplifiers are the most promising electron devices not only for high-power and high-voltage applications but also for mm-wave and THz wireless communications in 5th generation (5G) and next-generation mobile communications systems. In this study, we fabricated nanoscale-gate GaN-based high electron mobility transistors (HEMTs) on sapphire, SiC and GaN substrates and investigated the effect of InAlN barrier thickness on device performance to improve the fT and fmax. As a result, we successfully obtained high fmax of 287GHz and fT of 228GHz at the InAlN barrier thickness of 3nm for the 45nm-gate In0.18Al0.82N/AlN/GaN MES-HEMT on GaN substrate. In addition, we measured their output power characteristics at 70GHz and found that the 45nm-gate GaN MIS-HEMT respectively demonstrated about 7-times and 4-times higher output power (Pout) and P1dB compared with a 50nm-gate InP-based HEMTs with 520GHz-fT and 425GHz-fmax.