Numerical modeling of reduction in surface-related lags and current slump in GaAs FETs

We perform a two-dimensional transient analysis of field-plate GaAs MESFETs in which surface states are considered. Quasi-pulsed current-voltage curves are derived from the transient characteristics. It is shown that drain lag and current slump due to surface states are reduced by introducing a field plate because fixed potential at the field plate leads to reducing trapping effects by the surface states. Dependence of lag phenomena and current slump on field-plate length and SiO₂ passivation layer thickness is also studied, indicating that the lags and current slump can be completely removed in some cases.