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

(Al(0.7)Ga(0.3))(0.5)In(0.5 )P/In(0.15)Ga(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(m )=368 mS/mm and I(DS)=326 mA/mm were measured, respectively, for a device with a gate length of L(G)=0.35 mum. Although using self-aligned ohmic contacts, the devices showed very small output conductance of g(d) 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