| 摘要 |
PURPOSE:To vary the resistance value of an impurity region by forming the opposite conductivity type impurity region in one conductivity type semiconductor substrate, and forming metal electrodes through an insulating film on the impurity region, and applying a variable voltage to the metal electrodes. CONSTITUTION:A variable voltage is applied to metal electrodes 12 formed through an insulating film 13 on a P-type impurity region 11 to vary a resistance value between connecting terminals A, B. More particularly, when a positive voltage is applied to a control input C, the electrode 12 becomes positive, electrons are collected on the surface of the region 11 directly under the film 13, the effective sectional area of the region 11 is reduced to increase a resistance value between connecting terminals A, B. When a negative voltage is, on the contrary, applied to the control input C, the electrode 12 becomes negative, holes are gathered on the surface of the region 11 directly under the film 13, a current tends to readily flow in a channel with the holes. Thus, the resistance values between the connecting terminals A and B is reduced.
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