Multimillion Atom Simulations with NEMO 3-D

TL;DR

NEMO 3-D is a comprehensive atomistic modeling tool capable of simulating large-scale nanostructures, integrating quantum mechanics and material science to aid in the design of advanced nanodevices.

Contribution

The paper introduces NEMO 3-D, a novel atomistic simulation platform that handles millions of atoms for detailed nanostructure analysis, combining strain and electronic structure calculations.

Findings

Successfully modeled quantum dots with strain and piezoelectric effects

Simulated phosphorus impurities in silicon for quantum computing

Analyzed SiGe nanowires and quantum wells with atomistic detail

Abstract

The rapid progress in nanofabrication technologies has led to the emergence of new classes of nanodevices and structures. At the atomic scale of novel nanostructured semiconductors the distinction between new device and new material is blurred and device physics and material science meet. The quantum mechanical effects in the electronic states of the device and the granular, atomistic representation of the underlying material become important. The variety of geometries, materials, and doping configurations in semiconductor devices at the nanoscale suggests that a general nanoelectronic modeling tool is needed. The Nanoelectronic Modeling tool (NEMO 3-D) has been developed to address these needs. Based on the atomistic valence-force field (VFF) method and a variety of nearest-neighbor tight-binding models, NEMO 3-D enables the computation of strain for over 64 million atoms and of electronic structure for over 52 million atoms, corresponding to volumes of (110nmx110nmx110nm) and (101nmx101nmx101nm), respectively. This article discusses the theoretical models, essential algorithmic and computational components, and optimization methods that have been used in the development and the deployment of NEMO 3-D. Also, successful applications of NEMO 3-D are demonstrated in the atomistic calculation of single-particle electronic states of (1) self-assembled quantum dots including long-range strain and piezoelectricity; (2) stacked quantum dots ; (3) Phosphorus impurities in Silicon used in quantum computation; (4) Si on SiGe quantum wells (QWs); and (5) SiGe nanowires.