A two-dimensional self-consistent numerical model for high electron mobility transistor

A new two-dimensional self-consistent numerical model for a high-electron-mobility transistor (HEMT) is presented. In previous two-dimensional models, the quantization of electrons in the quantum well has been treated by using a triangular well approximation in which the width of the quantum well is assumed to be zero and the quantized electrons are assumed to reside right at the heterojunction. The authors do not make the above assumptions. Instead, the spatial spreading of the electron concentration in the quantum well normal to the heterojunction is taken into account by solving Schrodinger´s and Poisson´s equations self-consistently. The Boltzmann transport equation, in the form of a current continuity equation, and an energy balance equation are solved to obtain the transient and steady-state transport behaviour. The I _d-V_d characteristics, transconductance, gate capacitance, and unity-gain frequency of a single quantum-well HEMT are discussed. Also discussed are the dependencies of the device performance on the gate length and the doping concentration of the AlGaAs layer