Impact of Reduced Gate-to-Source Spacing on Indium Phosphide High Electron Mobility Transistor Performance

Indium phosphide (InP)-based high electron mobility transistors (HEMTs) with an offset gate enable higher maximum oscillation frequency (f(MAX)) values because of the resulting reduction in gate-to-source resistance. Following this approach, improved direct current (DC) characteristics and cutoff frequencies (f(T)/f(MAX) > 410/710 GHz withL(G) = 50 nm) are shown with respect to centered gate devices. However, HEMTs with an offset gate show degraded noise performances compared with centered gate devices because of a higher gate leakage current. The results show that offsetting the gate closer to the source is not desirable for ultra-low-noise performance.