A new self-aligned recessed-gate GaAs MESFET is developed using RIBE for recess etching. Recess-etching depth can be precisely controlled by RIBE with BCl3 etching gas. Barrier height and ideality factor of the Schottky contact formed on 200-V bias-voltage RIBE etched surface are 0.8 V and 1.2, respectively after 400 annealing. A very short gate-length is realized simply using the sidewall formation and the conventional photolithography. Furthermore, a self-alignment of ohmic electrodes and N+-layers to a gate electrode is realized to minimize the source resistance. The 0.3-µm gate-length MESFET fabricated on a wafer with the carrier concentration of 1.21018 cm-3 grown by MBE shows the transconductance as high as 415 mS/mm.