| 摘要 |
PURPOSE:To improve a gate reverse dielectric strength and a drain dielectric strength by forming a P-type layer on a boundary between a semi-insulating substrate and an active layer from under a gate electrode to under a drain electrode to increase a gate capacity and to alleviate a gate electrode end electric field without reducing a mutual conductance. CONSTITUTION:A shallow P-type GaAs layer 6 is formed by ion implanting of Be, Mg or the like on that part of a boundary between a semi-insulating substrate 1 and an active layer 5 extending from under a gate electrode 9 to under a drain electrode 8. The layer 6 alleviates an electric field concentration at the end of the gate electrode to have an action to prevent the gate and the drain from avalanche-multiplying therebetween. Thus, the dielectric strength of the gate electrode and the dielectric strength of the drain are improved. Since a depleted layer is not formed on the surface between the gate and the drain, the gate capacity is not increased and the mutual conductance is not reduced.
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