COMPUTER SIMULATION OF QUANTUM TRANSPORT IN HIGH ELECTRON MOBILITY TRANSISTOR PART 1: THE BOLTZMANN-POISSON-SCHROEDINGER SOLVER

摘要

A self-consistent Boltzmann-Poisson-Schroedinger simulator for High Electron Mobility Transistor is presented. The quantization of electrons in the quantum well normal to the heterojunction is taken into account by solving the two higher moments of the Boltzmann equation along with the Schroedinger and Poisson equations, self-consistently. The Boltzmann's 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 behavior. The numerical instability problems associated with the simulator are presented, and the criteria for smooth convergence of the solutions are discussed. The current-voltage characteristics, transconductance, gate capacitance, and unity-gain frequency of a single quantum well HEMT are discussed. It has been found that a HEMT device with a gate length of 0.7 μm and with a gate bias voltage of 0.625 V, has a transconductance of 579.2 mS/mm, which together with the gate capacitance of 19.28 pF/cm, can operate at a maximum unity-gain frequency of 47.8 GHz.