High-frequency InA1N/GaN HFET with an f(T) of 350 GHz

Scaled InA1N/GaN heterostructure field-effect transistors ( HFETs) with high unity current gain cut-off frequency (f(T)) were realized by employing nonalloyed regrown n(+)-GaN Ohmic contacts, in which the source-to drain distance (L) was scaled to 600 nm. By processing optimization of dry etching and n(+)-GaN regrowth, a low total Ohmic resistance of 0.16 Omega.mm is obtained, which is a recorded value regrown by metal organic chemical vapor deposition (MOCVD). A 34 nm rectangular gate was fabricated by self-aligned-gate technology. The electrical characteristics of the devices, especially for the RF characteristics, were improved greatly after the reduction of ohmic resistance and gate length. The fabricated InAIN/GaN HFETs show a low on resistance (R-on) of 0. 41 Omega.mm and a high drain saturation current density of 2.14 A/mm at V-gs =1 V. Most of all, the device shows a high f(T) of 350 GHz, which is a recorded result reported for GaN-based HFETs in domestic.