| 摘要 |
PURPOSE: To form a multilayered semiconductor device having a plurality of conducting paths without exposing a lower layer to form a metal contact, by arranging a first contact which electrically is in contact with two layers from an exposed surface, a second contact which electrically is in contact with the uppermost layer from the exposed surface, and a controlling means which sequentially and selectively depletes charge carriers in the two layers. CONSTITUTION: A doped GaAs layer 20 having an exposed surface 22 is formed. A first contact 24 is stuck from an upper layer 22 of a device 10 so as to stretch passing all layers. A second contact 26 is stuck so as to electrically be in contact with an upper layer 20. A depletion controlling means 32 is stuck on the upper surface 22 between the contacts 24 and 26. When a proper bias voltage is applied to the controlling means 32, charge carriers are depleted in order through a layer of the device 10 from the layer 20. A current path 40 passes through the layer 20 and is turned into a path in which a current flows when a bias voltage lower than a specified threshold voltage is applied to an electrode 32. When a voltage higher than the threshold voltage is applied, a depletion region 34 having a boundary 36 stretching as far as a layer 18 is formed. A current flows between the contact 24 and the contact 26 along a layer 16. |
