2-D simulation of degenerate hot electron transport in MODFETs including DX center trapping

Abstract

A comprehensive 2-D hydrodynamic energy model which is capable of describing nonstationary electron dynamics and nonisothermal transport within submicrometer MODFETs (TEGFETs or HEMTs) is presented. The model accounts for carrier degeneracy, deep DX center levels, and conduction outside the quantum well, thereby including bulk and parasitic MESFET effects. A technique for handling carrier degeneracy is presented. The authors also present two techniques developed to overcome the complexity of solving the coupling between the model nonlinear partial differential equations (PDEs). These cover DX center trapping kinetics and the energy derivatives in the Jacobian, particularly regarding the energy-conservation equation. The model is so informative that it highlights the main physical phenomena which govern device behavior such as velocity overshoots, stationary domain formation, buffer injection, back injection, and local longitudinal field inversion at the gate entrance of the channel. The model is systematically used to predict the DC and small-signal performance of submicrometer gate AlGaAs-GaAs MODFETs operating at room temperature