| 摘要 |
PURPOSE:To obtain a high electron mobility transistor with a Schottky electrode, electrostatic capacitance between gate-sources thereof is small, cut-off frequency thereof is high, high-frequency characteristics thereof are excellent and gate dielectric strength thereof is large. CONSTITUTION:An un-doped layer 31 in three layers constituting an electron supply layer 3 has a function preventing ionic scattering. A high-concentration N type layer 32 satisfies conditions in which a two-dimensional electronic gas having surface concentration of approximately 10<11>/cm<2> or more necessary and sufficent as a conductive medium of the semiconductor device is generated, but its thickness is very thin. The third, an n type layer 33 as an uppermost layer satisfies conditions necessary and sufficient for allowing the formation of a depletion layer to the lower section of a gate electrode, and has not thickness more than required. Consequently, the thickness of the electron supply layer 3 is sufficiently thin and electrostatic capacitance between the gate-source is reduced sufficiently, cut-off frequency is improved, and high-frequency characteristics are enhanced. Dielectric strength between the gate-sources is also improved because impurity concentration in the N type layer 33 has been reduced properly. |
