Semiconductor device using a barrier layer between the gate electrode and substrate and method therefor

An enhancement mode semiconductor device has a barrier layer disposed between the gate electrode of the device and the semiconductor substrate underlying the gate electrode. The barrier layer increases the Schottky barrier height of the gate electrode-barrier layer-substrate interface so that the portion of the substrate underlying the gate electrode operates in an enhancement mode. The barrier layer is particularly useful in compound semiconductor field effect transistors, and preferred materials for the barrier layer include aluminum gallium arsenide and indium gallium arsenide.