A semiconductor device and its manufacturing method. The semiconductor device
has
a semi-insulating GaAs substrate 310, a GaAs buffer layer 321 that
is formed on the semi-insulating GaAs substrate 310, AlGaAs buffer layer
322, a channel layer 323, a spacer layer 324, a carrier supply
layer 325, a spacer layer 326, a Schottky layer 327 composed
of an undoped In0.48Ga0.52P material, and an n+-type
GaAs cap layer 328. A gate electrode 330 is formed on the Schottky
layer 327, and is composed of LaB6 and has a Schottky contact
with the Schottky layer 327, and ohmic electrodes 340 are formed
on the n+-type GaAs cap layer 328.
