Enhancement of f\mathrm {max} to 910 GHz by Adopting Asymmetric Gate Recess and Double-Side-Doped Structure in 75-nm-Gate InAlAs/InGaAs HEMTs.

A high maximum frequency of oscillation ( f\mathrm {{max}} ) of 910 GHz was achieved at InAlAs/InGaAs high-electron mobility transistors (HEMTs) with a relatively long gate length ( LG ) of 75 nm by adopting an asymmetric gate recess and a double-side-doped structure. The f\mathrm {{max}} improved significantly by extending the drain-side gate recess length ( L\mathrm {{RD}} ) to 250 nm; meanwhile, the source-side gate-recess length ( L\mathrm {{RS}} ) was kept to 70 nm. The improvement in f\mathrm {{max}} was due to a decrease in the drain output conductance ( gd ) and drain-to-gate capacitance ( \textC\mathrm {{GD}} ) after the extension of L\mathrm {{RD}} . gd was further suppressed by applying a double-side-doped structure to the InP-based HEMTs. A reduction in gd resulted in a drastic improvement in f\mathrm {{max}} even though LG was a longer value. [ABSTRACT FROM AUTHOR]