Effect of gate-recess structure on the high frequency performance of ultra-fast InP-based HEMTs - asymmetric gate-recess fabrication and characterization

摘要

InP-based InGaAs/InAlAs high electron mobility transistors (HEMTs) are the fastest transistors at present and key devices for the future millimeter-wave and optical communications. In this paper a self-aligned asymmetric gate-recess structure for the ultra-list InGaAs/InAlAs HEMTs is developed in order to investigate the effect of the gate-recess structure on their high frequency performances. A 60-nm-gate HEMT with a longer drain-side recess length (Lrd) exhibits a much-improved maximum oscillation frequency (f{sub}(max)) of 503 GHz compared to that (281 GHz) with a symmetric recess structure mainly due to a decrease in a drain conductance (gd) and a gate-drain capacitance (Cgd). This result indicates that the longer Lrd results in a longer depletion area at the drain end of the gate and then alleviate electric field between gate and drain.