Patent ID: 6967360

Claim:
A pseudomorphic high electron mobility transistor comprising: a semi-insulating GaAs substrate; an epitaxial layer including a plurality of layers sequentially stacked on said GaAs substrate, said sequentially-stacked layers including: a GaAs buffer layer; an AlGaAs buffer layer; an undoped InGaAs channel layer; a first undoped AlGaAs spacer layer; a carrier supply layer; a second undoped AlGaAs spacer layer; an undoped InGaP Schottky layer; and a doped GaAs cap layer; a source electrode and a drain electrode formed on and in ohmic contact with said doped GaAs cap layer; and a gate electrode formed on said undoped InGaP Schottky layer so that said gate electrode extends through said doped GaAs cap layer, said gate electrode being composed of material whose main constituents are La and B.