| 摘要 |
PURPOSE:To control the impedance of a conductive path between separately provided two electrodes by controlling the electron density of an electron accumulation layer occurring around a hetero junction surface by a difference in electron affinity by the voltage in a control electrode. CONSTITUTION:A nonadditive or N<-> type GaAs channel layer 22 and an N<+> type Al0.3Ga0.7As electron supply layer 21 are epitaxially formed on an insulating substrate 20. After applying the removal of etching to the layer 21 by consisting an Al electrode 30 as a mask, the N<+> layer 22' is formed by ion injection to provide Al electrodes 31, 32. The N type Al0.3Ga0.7 makes a depletion layer having a Schottky barrier of VD1=1.5V and a thickness of about d1=550Angstrom between Al and also a depletion layer having a band gap of VD2=0.4V and a thickness of d2 280Angstrom . Al0.3Ga0.7As is epsilon=11 and d0<d1+d2 is formed when the thickness d0 of the layer 21 is composed as 800Angstrom and the layer 21 is completely depleted and an electron accumulation layer is formed in the channel layer 22 to function as a depletion FET and switching speed is improved, while d0 has a predetermined relation with VD1, VD2. |
