Comparison of Monte Carlo and NEGF Simulations of Double Gate MOSFETs

Abstract

The present work compares the simulation results of the two-dimensional full band Monte Carlo simulator (MOCA) developed at the University of Illinois at Urbana-Champaign and the two-dimensional quantum simulator (NanoMOS) developed at Purdue University. Double-gate MOSFETs of three body thicknesses – t_Si = 4, 3 and 2 nm—were considered in this study. For a body thickness of 4 nm, the conduction band profiles and sheet charge densities obtained from MOCA and NanoMOS almost overlap, particularly for high gate and drain-to-source biases. However, as the body thickness is reduced, quantum effects are captured more naturally in NanoMOS since MOCA only uses a simple quantum correction scheme, with an otherwise semi-classical model. However, even for thinner devices, since MOCA makes use of a detailed band structure and scattering model, high energy transport is better reproduced by the Monte Carlo procedure. A particle description is appealing for nanoscale simulation, in order to reproduce the granularity aspects of the transport. Comparisons with a quantum model based on continuum flow equations as in NanoMOS should provide valuable insight to better incorporate the quantum mechanical aspects in a practical particle-based model.