A Surface-Potential-Based Compact Model for Study of Non-Linearities in AlGaAs/GaAs HEMTs

We present a continuous surface-potential- based electro-thermal compact model suitable for the study of intermodulation distortion IMD in GaAs HEMT devices. We have developed a precise analytical calculation for the position of the Fermi level E_f in these devices from a consistent solution of Schrödinger´s and Poisson´s equations. The accuracy of our calculation is of the order of pico-volts. E_f is used to define the surface-potential ψ and subsequently derive the drain current I_d. We use the developed I_d model for prediction of IMD in these devices using Volterra series method. The model is in excellent agreement with experimental IMD data. The impact of various real device effects like self- heating, mobility degradation etc., on the non- linear behavior of the device is analyzed using the model.