Atomistic simulation of nanowire transistors

Luisier, Mathieu (Integrated Systems Laboratory, ETH Zurich); Schenk, Andreas

Source: Journal of Computational and Theoretical Nanoscience, v 5, n 6, June, 2008, p 1031-1045

Publisher: American Scientific Publishers

Abstract: At the nanometer scale, the computer simulation of electronic transport cannot be conceived without including quantum-mechanical effects as well as the atomic granularity of the simulation domain. In this review we present a three-dimensional quantum transport simulator based on the sp³d⁵s* semi-empirical tight-binding (TB) method that fulfills these two requirements. The integration of the multi-band TB model into a transport code is only possible, if open boundary conditions (OBCs) are introduced. The available procedures to calculate OBCs in three-dimensional structures are computationally too intensive, since they take the form of a generalized eigenvalue problem or require iterative solvers. Therefore, an improved method based on the scattering-boundary approach is reviewed in this work. It significantly reduces the computational burden associated with the OBCs calculation. Furthermore, it can be formulated either in the Non-Equilibrium Green's Function or in the Wave Function formalism, it works for any channel orientation, material composition, or cross section shape, and it is self-consistently coupled to the three-dimensional computation of the electrostatic potential in the device. These features allow the analysis and the comparison of nanowire field-effect transistors (FETs) with transport along the [100], [110], [111], and [112] crystal axis. Hence, their ON-current, subthreshold swing, and interface roughness sensitivity are investigated. Copyright © 2008 American Scientific Publishers All rights reserved. (55 refs.)

terms:  Quantum chemistry  -  Computational methods  -  Computer simulation  -  Electric wire  -  Quantum electronics  -  Three dimensional