| 摘要 |
PURPOSE:To decrease a parasitic capacitance by forming eaves portion of an insulating film on the concave portion in a semiconductor substrate, filling the hole by an electrode, and forming a cavity under the eaves portion. CONSTITUTION:A GaAs active layer 2 is provided on a semi-insulating GaAs substrate 1, and the layer 2 is covered by SiO2 12. A hole 13 is provided in SiO2 12, and the layer 2 is etched, thereby a concave portion 11 having the eaves of SiO2 is formed. Then, Al is evaporated, photoetching is performed, thereby an electrode 10 is formed. If the width of the electrode 10 is shorter than the width of the gap 11, the effective length L of the electrode 10 is determined by the hole 13 of the insulating film 12, the cross-sectional area becomes large, and the gate resistance is decreased. Furthermore, since the electrode 10 contacts with a channel portion via the insulating film 12 and the gap 11, except the Schottky barrier portion; the parassitic capacitance becomes extremely small. Therefore, the Schottky barrier FET for the ultra high frequency characterized by low noises and a high gain can be obtained. |
