2-D Analytical Model for Current–Voltage Characteristics and Transconductance of AlGaN/GaN MODFETs

A threshold-voltage-based 2-D analytical model for the current-voltage characteristics of the AlGaN/GaN modulation-doped field-effect transistors (MODFETs) is presented. In this paper, the conventional charge-control model is improved by employing the Robin boundary condition when solving the 1-D Schrodinger equation in the low longitudinal-field region and introducing an adjustable eigenvalue during the solution of the 2-D Poisson's equation in the velocity-saturation region. A modified Polyakov-Schwierz mobility model, as well s a low-field mobility model, has been developed. In addition, the nonlinear polarization effects at the AlGaN/GaN interface and the parasitic source/drain resistances are incorporated. Our model predicts the drain current of a second-order continuity, and both the transconductance and output conductance can be determined analytically. We validate the model with experimental data for and MODFETs, respectively, and obtained good agreements.