(AL0.7GA0.3)(0.5)IN0.5P IN0.15GA0.85AS/GAAS HETEROSTRUCTURE FIELD-EFFECT TRANSISTORS WITH VERY THIN HIGHLY P-DOPED SURFACE-LAYER/

(Al0.7Ga0.3)(0.5)In0.5P/In0.15Ga0.85As/GaAs Heterostructure Field Effe ct Transistors were realized for the first time using low pressure met al organic chemical vapor deposition on GaAs substrates. Maximum extri nsic transconductance and saturation current of g(m)= 368 mS/mm and I- DS= 326 mA/mm were measured, respectively, for a device with a gate le ngth of L(G)=0.35 mu m. Although using self-aligned ohmic contacts, th e a devices showed very small output conductance of g(d) less than or equal to 10 mS/mm and high gate-drain breakdown voltage of V-BrGD=19 V . The cut-off frequencies were determined to be f(T)=52 GHz and f(max) =120 GHz.