Monte Carlo study of impact ionization phenomena in small geometry MOSFET's

Abstract

We developed a multi-valley Monte Carlo simulator in which realistic physical parameters based on ab-initio calculations are implemented. A nonlocal impact ionization coefficient in exponentially increasing field is extracted using the Monte Carlo simulator. On the basis of the new nonlocal impact ionization coefficient, an analytical substrate current expression for n-MOSFET's is derived. The new substrate current expression clarifies the reason why a reported theoretical characteristic length used in a pseudo two-dimensional MOSFET model differs from empirically derived ones. The nonlocal impact ionization coefficient implemented in a device simulator demonstrates that the new coefficient can predict substrate current correctly in the framework of the drift diffusion model.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>