INGAP INGAAS HFET WITH HIGH-CURRENT DENSITY AND HIGH CUTOFF FREQUENCIES/

Doped channel pseudomorphic In0.49Ga0.51P/In-0.20 Ga0.80As/GaAs hetero structure field effect transistors have been fabricated on GaAs substr ate with 0.25 mu m T-gates and self-aligned ohmic contact enhancement, By introducing the channel doping and reducing the series resistances , a high current density of 500 mA/mm is obtained in combination with cut-off frequencies of f(T) = 68 GHz and f(max) = 160 GHz, The channel doping did not affect the RF-performance of the device essentially, w hich is additionally reflected in noise figures below 1.0 dB with an a ssociated gain of 14.5 dB at 12 GHz.