Hot electron model for GaAs metal semiconductor field effects transistors.

We propose a new model for GaAs MESFFETs that we incorporated into a circuit simulator. The improvements of the model (compared to standard MESFET models) include - account for electron heating that is non-uniform along the device channel, with different electron temperatures at the source and drain sides of the cannel - account for the threshold voltage dependence on the drain-tosource voltage, - account for the channel conductance dependence on the drain voltage below the drain-to-source saturation voltage, - account for parasitic gate-to-source and and gate-to-drain leakage resistances determining the gate current at small gate voltages. The account for electron heating is based on the new technique for measuring the electron temperature in the channel. This technique utilizes the exponential dependence of the gate current in GaAs MESFETs on electron temperature in the channel. Using this new technique we measured the electron temperature as a function of the gate and drain bias in depletion mode ion-implanted GaAs MESFETs. The results of the calculations are compared with experimental data for depletion mode GaAs MESFETs that we fabricated by direct ion-implantation into a semi-insulating GaAs substrate. The model yields an excellent fit to the drain and gate current-voltage characteristics of GaAs MESFETs in the entire range of gate and drain voltages. (-y-)