A modified charge-control model for HEMTs

A modified model for the charge control in HEMT devices is presented. The model is based on the solution of Poisson´s equation in the AlGaAs layer using an accurate numerical method. The model assumes a non-uniform ionized donor concentration, this nonuniformity is assumed to follow the Fermi-Dirac statistics. The free carrier concentration in AlGaAs is deduced from the drift/diffusion equation assuming zero current density at the heterointerface. The obtained results have been compared with other models. The effects of structural and processing parameters on the charge control mechanism are extensively examined and optimization of these parameters for design of high performance devices are also discussed