In this paper modeling of powerful GaAs Metal Semiconductor Field Effect Transistor (MESFET) was carried out, I-V
characteristics with breakdown voltage of MESFET were obtained. With the help of this model optimal characteristics of
structure for power MESFET were determined. Recommendations for value of Schottky barrier were proposed. Also
breakdown voltage was calculated. More over temperature dependencies of I-V characteristics of MESFET were studied.