High-Gain Millimeter-Wave AlGaN/GaN Transistors

In this paper, the fabrication and performance of common-source (CS) and common-gate transistors for operation at millimeter-wave frequencies are presented. The AlGaN/GaN devices have a gate length of 100 nm and yield a high maximum transconductance of above 550 mS/mm with a very low contact resistance of less than 0.12 Ω·mm. The baseline technology with its optimized epitaxial structures and their transition frequency of more than 80 GHz allows reproducible designs for monolithic microwave integrated circuits up to the W-band frequency range (75-110 GHz). In addition, GaN dual-gate (DG) devices were developed for substantial improvement of the bandwidth of the devices and of the gain per stage on circuit level. This paper discusses the advantages of the DG devices in power gain over the CS high electron mobility transistors for millimeter-wave applications.