Wideband AlGaN-GaN HEMTs on SiC for low noise applications

AlGaN-GaN high electron mobility transistors (HEMTs) have attracted attention because of their extremely high current drive capability and high power performance. Although these GaN-based FETs are primarily considered for high power and high temperature applications, it is important to investigate their microwave noise characteristics. Indeed, the only report in literature (Ping et al, Electron. Lett. vol. 36, pp. 175-176, 2000) to date has shown that AlGaN-GaN HEMTs do have respectable noise properties that are comparable to those of AlGaAs-GaAs HEMTs. Specifically, we have recently reported on 0.25 /spl mu/m AlGaN-GaN HEMTs with a minimum noise figure (NF/sub min/) of 0.77 dB at 5 GHz and a NF/sub min/ of 1.06 dB at 10 GHz. These results are quite counter-intuitive to what might be expected due to the material properties, and especially the defect density, of GaN. However, the results do motivate further investigations of the noise properties of AlGaN-GaN HEMTs. In this paper, we report our latest results on DC, RF, and high frequency noise characteristics of AlGaN-GaN HEMTs, demonstrating a record bandwidth of 100 GHz and NF/sub min/ of 0.53 dB at 8 GHz.