Compound semiconductor device with a particular gate structure

Claim 1

A compound semiconductor device comprising: a semi-insulating compound semiconductor substrate; a plurality of epitaxial compound semiconductor layers successively disposed on said substrate including an InGaAs layer as the compound semiconductor layer furthest from said substrate; a groove penetrating through said InGaAs layer and into at least one other of said compound semiconductor layers forming side surfaces on some of said compound semiconductor layers; an insulating film disposed on the side surfaces and on part of one of said compound semiconductor layers within the groove, leaving part of the compound semiconductor layer in the groove exposed, said insulating film having opposed internal surfaces generally within the groove and end parts extending beyond the groove generally parallel to and spaced from said compound semiconductor layers; a gate electrode disposed in the groove, on the internal surfaces of said insulating film, and directly contacting and forming a Schottky barrier with said compound semiconductor layer exposed in the groove; and source and drain electrodes disposed on said InGaAs layer at opposite sides of the groove respectively self-aligned with the end parts of the insulating film.