Gate-lag effects in AlGaAs/GaAs power HFET's

Gate-lag effects have been characterized in as-fabricated and hot-carrier-stressed power AlGaAs/GaAs HFET's and then compared with transconductance frequency dispersion measurements and studied by means of numerical simulations accounting for the occupation dynamics of surface deep-acceptor traps. We have found a clear direct correlation between the amount of gate-lag and of transconductance dispersion. The gate-lag tam-off transients of increasingly degraded devices have been accurately simulated by suitably increasing the surface trap density. (C) 2001 Elsevier Science Ltd. All rights reserved