Analysis of surface-state effects on gate-lag phenomena in recessed-gate and buried-gate GaAs MESFETs

Gate-lag or slow current transient in GaAs MESFETs is studied by two-dimensional analysis including surface-state effects. It is shown that in a recessed-gate structure, the gate-lag is reduced to some extent by increasing the recess depth, but it may not be so much suppressed as expected because the surface states around the gate affect the turn-on characteristics. However, by introducing the buried-gate structure where the gate electrode is attached to the vertical planes of the recess and (also) to the same planes as the drain electrode, the surface-state effects are minimized, and the gate-lag can be greatly reduced.