| 摘要 |
PROBLEM TO BE SOLVED: To provide a hetero-junction field-effect transistor having a high forward breakdown voltage between the gate and source. SOLUTION: On a semiconductor substrate 1, a channel layer 3, a carrier- supply layer 4, a first Schottky contact layer 5 consisting of AlGaAs, a second Schottky contact layer 6 consisting of AlGaAs having an Al composition ratio smaller than that of the first Schottky contact layer 5, and a contact layer 7 are sequentially formed. The contact layer 7 is partially removed to form a groove 9. Inside the groove 9, a gate electrode 11 is formed extending from a partial region of the surface of the second Schottky contact layer 6 to the surface or the inside of the first Schottky contact layer 5. Since the Schottky barrier level is heightened, the high forward breakdown voltage between the gate and the source can be obtained. Since the distance between the gate electrode and the channel layer is reduced, large mutual conductance is obtained.
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