| 摘要 |
A MESFET comprises an active layer on a semi-insulating semiconductor substrate 2 which is divided into a first portion 12 which has a shallow thickness to provide a pinch-off voltage and is formed directly under a gate electrode 3 and second portions 11, 13 which are doped with a higher dose of impurity per unit area than the first portion and formed on opposite sides of it. The interfaces between the first portion 12 and the second portions 11, 13 are spaced from the gate electrode 3 by substantially the thickness of the first portion 12 thereby to provide an optimum distance between each of the second portions 11, 13 and the gate electrode 3. Such a MESFET has a small gate-source capacity, a small gate-drain capacity, a small gate-source resistance, a small gate-drain resistance, and a large transconductance gm, thereby achieving an ultra-high-frequency operation, an ultra-high-speed operation, and a low noise characteristic. |
