Dependence of maximum gate-drain potential in GaAs MESFET's upon localized surface charge

Experimental data has become available which suggests that the maximum useful gate-drain voltage of a GaAs MESFET tends to increase as the gate length is increased. It is shown by computer simulation that, to explain this observation, it is necessary to include an excess electron charge localized at, or close to, the semiconductor surface at the drain edge of the gate.