60-nm GaN/AlGaN DH-HEMTs with 1.0 Ω·mm Ron, 2.0 A/mm Idmax, and 153 GHz fT

GaN-based HEMTs offer a unique combination of high electron velocity and high breakdown field making them t he prime candidate for the highest performance millimeter-wave solid-state power am plifiers (PAs). Recently, we have demonstrated GaN MMIC PAs with an output power of 500 mW at W-band frequency range [1]. The device high frequency performance has been significantly im proved during the past y ears through vertical epitaxial scaling with double-hetero (DH) HEMT structures using an AlGaN back barrier [2] and reduction of gate length (L
g
) down to 30 nm [3]. One of technical challenges for further device scaling is reduction of parasitic resistances. Various approaches including alloyed contact to an n
⁺
-GaN cap layer, ion implantation, and a multi-channel structure were attempted. However, a resulting on- resistance (R
on
) is typically larger than 1.6 Ω·mm.