Heterojunction Schottky gate MESFET with lower channel ridge barrier

This invention relates to an FET with an extremely short channel formed by the apex of a substrate ridge structure protruding upward through the channel layer toward a Schottky-barrier gate contact. The device is formed by etching a modulation-doped substrate to form an upwardly protruding ridge with the apex modulation-doped. A semiconductor layer is then disposed over the substrate surface with the protruding ridge to obtain an epitaxial interface therebetween. Source and drain regions are doped into the semiconductor layer on opposite sides of the ridge structure. Finally, ohmic contacts are formed on the semiconductor layer over the source and drain regions and a Schottky-barrier metalization is deposited on the semiconductor layer above the ridge structure. This device has a very short channel, a low transit time, a low gate capacitance, and an enhanced transconductance.