| 摘要 |
PURPOSE:To obtain a capacity element having little dependency on voltage by providing an N<+> layer divided into a plurality within a P type Si region. CONSTITUTION:An N<-> epitaxial layer on a P type Si substrate 1 is separated by a P<+> layer 3, a P layer 4 is provided and N<+> layers 5-7 are made in the layer 4. An electrode 8 is attached to the central layer 5 and positive voltage is applied thereto to place the layers 6 and 7 surrounding the layer 5 concentrically in a floating state. Since the distance between the respective layers is small, a depletion layer reaches them with ease. When negative voltage is given by an electrode attached to the P layer 4, the depletion layer expands between the layers 5 and 4 and the junction capacity is reduced with the increase in voltage. When the voltage is increased further, the depletion layer reaches the layer 6, the layers 5-6 are made to have the same potential, thus the depletion layer having a large area is formed, and the junction capacity is sharply increased. This action is repeated likewise also for the layer 7, whereby the capacity is changed in an indented form. By selecting the shape, arrangement and difference in density from the layer 4 of the layers 5-7, the element wherein the change in capacity is little dependent on voltage can be obtained. |
