This paper presents a two-dimensional numerical analysis method and program for self-aligned GaAs MESFET.by using finite-differential method. For different n￣+depth

the distributions of potential

electric field and carrier concentration along the channel and the current-voltage characteristic curve are studied. The results show that the deeper the n￣+ implanted depth

the bigger will the domain be. Reasonable Lgs and Lgd will improve the device breakdown voltage.