Parameter-free effective potential method for use in particle-based device simulations

We propose a novel parameter-free effective potential scheme for use in conjunction with particle-based simulations. The method is based on a perturbation theory around thermodynamic equilibrium and leads to an effective potential scheme in which the size of the electron depends upon its energy. The approach has been tested on the example of a MOS-capacitor by retrieving the correct sheet electron density. It has also been used in simulations of a 25-nm n-channel nano-MOSFET that requires very high substrate doping to prevent the punch-through effect which, on the other hand, leads to pronounced quantum mechanical space-quantization effects. We find that the use of the new effective potential approach gives correct experimentally verified threshold voltage shifts of about 220 mV and drain current degradation of about 30%. The largest contribution comes from the barrier field which is precomputed in the initial stages of the simulation. Thus, rough estimates on the role of quantum effects on device operation can be made by using the barrier field only.