Theoretical analysis of the DC avalanche breakdown in GaAs MESFET´s

The channel avalanche breakdown in GaAs MESFET´s has been investigated using nonstationary electron dynamics and an ionization coefficient taken as a function of average electron energy. Stationary high-field domains of different shapes and peak-field localization are calculated at the breakdown, depending on technological parameters, device geometry or gate bias. Design rules are given to obtain maximum saturated output power and a full-channel current breakdown voltage comparable to the one near pinchoff. In particular, it is found that both a recessed channel geometry and an increased gate-drain distance should yield the best device performances with a doping level not higher than about 1.2-10¹⁷cm^-3and a channel current Idssbetween 275 and 330 mA/mm.