| 摘要 |
PURPOSE:To make it possible to select and control a threshold value, by making the electron affinity of a third semiconductor layer, in which a gate electrode is provided, smaller than that of a first semiconductor layer and larger than that of a second semiconductor layer. CONSTITUTION:On a semi-insulating GaAs substrate 1, a non-doped GaAs layer 2, an Al0.4Ga0.6As layer 3 and N<+> type Al0.2Ga0.8As layer 4 are sequentially formed. A gate electrode 5 is arranged on the layer 4. The layer 4, on which the electrode 5 is formed, is made to be positioned on the higher energy side than the layer 2, in which a Fermi level forms a channel layer. Thus, the state, where a bias voltage corresponding to the difference in Fermi levels between both layers is applied, can be implemented without applying a voltage to the electrode 5. The difference in Fermi levels can be controlled by selecting the composition of a semiconductor layer. Therefore, the effect of selecting and controlling the threshold value of an FET can be obtained. |
