2-D physical modelling of ò-doped GaAs/AlGaAs HEMT

GaAs/AlGaAs is one the most prevalent material systems for High Electron Mobility Transistors (HEMTs) especially at very low temperatures because of its very high mobility under these conditions. In this work, full physical modelling of a GaAs/AlGaAs HEMT with lum gate length geometry is presented. The model is developed using 2-D ATLAS SILVACO[I] simulator and compared with measurements obtained from a similar HEMT fabricated at the University of Manchester using Molecular Beam Epitaxy (MBE). Models taking into account the effect of transverse and lateral electric fields on mobility, deep-level traps, Fermi-level pinning, carrier generation/recombination and tunnelling have been included and these have led to excellent agreements between modelled and experimental values. The mobility model used has the largest effect on simulated I-V curves and inclusion of deep-level traps in the AlGaAs buffer layer improved the model considerably by raising carrier confinement in the channel. © 2008 IEEE.