  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.
