75 nm T‐shaped gate for In 0.17 Al 0.83 N/GaN HEMTs with minimal short‐channel effect

Lattice‐matched InAlN/gallium nitride high electron‐mobility transistors with a 6 nm‐thick InAlN barrier layer were fabricated and characterised. By introducing a very thin InAlN Schottky layer, the short‐channel effect could be minimised. The devices with a gate length of 75 nm exhibited output resistance as high as 56.9 Ω mm together with a drain‐induced barrier lowering as low as 63 mV/V. The devices also demonstrated excellent high‐frequency characteristics such as a unity current gain cutoff frequency ( f T ) of 170 GHz and a maximum oscillation frequency ( f max ) of 210 GHz.