Novel HEMT layout: The RoundHEMT

Abstract
A novel HEMT layout with ringshaped gate is reported. This conception avoids the problems related to mesa etching at the active region and provides additional possibilities for circuit design. The layer structure of the investigated device is based on an Al-free InP/InGaAs material system. Transistors with a gate length of 0.7 µm show an fT of 40 GHz and an fmax of 117 GHz. These values are similar to results obtained with the conventional HEMT design.