Simulation of quantum confinement effects in ultra-thin-oxide MOS structures

The density-gradient approach to quantum transport theory is used to model the inversion layer profiles, threshold voltages and C-V characteristics of MOS capacitors with ultra-thin oxides and polysilicon gates. The results (without fitting parameters) are found to compare quite well with experimental data and with calculations made using quantum mechanics. Comparisons are also made with results obtained using previous phenomenological methods and these favor density-gradient theory as well, especially in its being physically meaningful and predictive. Overall, the results of this work show that density-gradient theory provides a physics-based approach to device modeling problems in which quantum confinement effects are significant that is simple enough for engineering applications.