(An) efficient methodology for atomic-level device simulations

Abstract

In recent years, as the channel length has been scaled to the level of several nanometers, the influence of individual atomic interactions has increased. Thus, a modeling approach at the atomic-level is necessary. However, atomic-level models such as density-functional theory and empirical tight-binding have large constraints in dealing with realistically-sized devices due to the huge computational burden. Herein, we propose an efficient scheme to systematically construct a reduced-sized, mode space Hamiltonian and applied it to nano-scale devices. The proposed method for the mode space approach extracts only the transport modes that contribute to the current within a pre-specified energy range and therby construct a reduced-sized mode space Hamiltonian. We have successively implemented the reduced transformation for the non-orthogonal Hamiltonian. Thus, highly efficient quantum-mechanical calculations based on the non-equilibrium Green’s function method are made possible. The methodology was extended for application to irregular atomic structures, and devices with impurities were simulated.