Al0.3Ga0.7As/GaAs metal-insulator-semiconductor-type field-effect transistor fabricated on an InP substrate

A metal-insulator-semiconductor-type Al0.3Ga0.7As/GaAs field-effect transistor with 1-μm-long by 145-μm-wide gates and intrinsic transconductance of 180 mS/mm has been demonstrated on an InP substrate. The dislocation propagation is minimized by incorporating a superlattice on InP, and a 1.5 μm undoped GaAs buffer layer is grown prior to the actual channel to ensure good quality of the 250 Å active layer. A channel mobility of 1920 cm2/(V s) and a carrier concentration of 1.28×1018 cm−3 have been measured at 300 K. The device exhibits excellent pinch-off, and the gate-to-source reverse breakdown voltage is greater than 5 V. The low output conductance of 2.5 mS/mm indicated small parallel conduction in the undoped GaAs buffer layer. Also, very little hysteresis was found in the current-voltage characteristics, implying few traps in the epilayer.