| 摘要 |
PURPOSE:To simplify the manufacturing process of MES-FET and to improve the yield by using a semiconductor having relatively high density-doped wide forbidden band width as a protective film on a channel, thereby enabling to form a gate electrode on the protective film. CONSTITUTION:A GaAs buffer layer 2, an N type GaAs layer 3 are formed sequentially on a semi-insulating GaAs substrate 1, and the surface of the layer 3 between a source electrode 5 and a drain electrode 6 is coated with an AlxGaal-xAs layer 11 of wide cap semiconductor. In this case, when the layer 11 is formed in relatively high density-doped n<+> type AlxGaa1-xAs (0<x<1), a vacant doner unit is formed, and the end 6 of the band is curved. Accordingly, the surface depletion layer of thin thickness (e.g., 500Angstrom ) can be suppressed. A gate electrode 4 is formed directly on the thus thin layer 11. |
