SELF-ALIGNED GaAs SCHOTTKY BARRIER GATE FET USING PREFERENTIAL ETCHING.

Preferential etching using a Br//2 - CH//3OH solution is applied to the fabrication of a Schottky barrier gate GaAs FET. The merits of this method are experimentally demonstrated. A short-length gate can be self-aligned extremely close to the source and drain without using critical mask alignment and photoetching of high accuracy. Devices are fabricated with 2 mu m and 5 mu m gate length in a 3 - 4 mu m thick N-type epitaxial layer of GaAs doped with 10**1**5 - 10**1**6cm** minus **3 carrier concentration grown on a semi-insulating GaAs substrate. The series resistance of a typical device is significantly small (10 OMEGA ) and the transconductance of 8 m mho is obtained in a device with a gate length of 5 mu m and a width of 500 mu m.