Enhancement Of F(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(max)) of 910 GHz was achieved at InAlAs/InGaAs high-electron mobility transistors (HEMTs) with a relatively long gate length (L-G) of 75 nm by adopting an asymmetric gate recess and a double-side-doped structure. The f(max) improved significantly by extending the drain-side gate recess length (L-RD) to 250 nm; meanwhile, the source-side gate-recess length (L-RS) was kept to 70 nm. The improvement in fmax was due to a decrease in the drain output conductance (g(d)) and drain-to-gate capacitance (C-GD) after the extension of L-RD. g(d) was further suppressed by applying a double-side-doped structure to the InP-based HEMTs. A reduction in g(d) resulted in a drastic improvement in f(max) even though L-G was a longer value.