(Al/sub 0.7/Ga/sub 0.3/)/sub 0.5/In/sub 0.5/P/In/sub 0.15/Ga/sub 0.85/As/Ga As heterostructure field effect transistors with very thin highly p-doped surface layer

(Al/sub 0.7/Ga/sub 0.3/)/sub 0.5/In/sub 0.5/P/In/sub 0.15/Ga/sub 0.85/As/Ga As Heterostructure Field Effect Transistors (HFETs) were realized for the first time using low pressure metal organic chemical vapor deposition on GaAs substrates. Maximum extrinsic transconductance and saturation current of g/sub m/=368 mS/mm and I/sub DS/=326 mA/mm were measured, respectively, for a device with a gate length of L/sub G/=0.35 /spl mu/m. Although using self-aligned ohmic contacts, the devices showed very small output conductance of g/sub d//spl les/10 mS/mm and high gate-drain breakdown voltage of V/sub BrGD/=19 V. The cut-off frequencies were determined to be f/sub T/=52 GHz and f/sub max/=120 GHz.< >