High-speed compound semiconductor device operable at large output power with minimum leakage current

摘要

A compound semiconductor device includes a cap layer formed on a channel layer and an insulating film formed on the cap layer, and a &Ggr;-shaped gate electrode is provided in a gate recess opening, wherein an extension part of the &Ggr;-shaped gate electrode extends over the insulating film toward a drain electrode, and the total thickness of the insulating film and the cap layer being is set such that the electric field formed right underneath the extension part of the gate electrode includes a component acting in a direction perpendicular to the substrate.