| 摘要 |
PURPOSE:To obtain an FET which has excellent noise characteristic by utilizing a combination of Si and GaAs or GaAlAs and forming a protecting film having extremely small surface level density of a boundary on an active layer. CONSTITUTION:A p<+>-Ga(Al)As 5 is formed on a semi-insulating GaAs substrate 1, its section is patterned in a trapezoidal shape, and the planar shape is patterned in a T shape. An n-GaAs 2 is arranged perpendicularly on a narrow projection 5a, and a gate electrode is formed with the projection 5a. After the surface is purified by Ar ion sputtering in vacuum, an n type GaAs active layer 2 and non-added Ga0.7Al0.3As semi-insulating layer 4 are laminated by a molecular beam epitaxial method. After the unnecessary part of the layer 4 is etched, electrodes S, D of Au-Ge-Ni alloy are formed, are alloyed at 420 deg.C in N2, Au- Zn is deposited on the exposed surface of the layer 5 as the junction region 3c of the gate, and is alloyed at 450 deg.C in N2, thereby forming a J-FET. In this structure, an SiO2 or Si3N4 is not used for the active layer or surface protective film, thereby reducing the surface level density and causing a low noise. |
