NANOSCALE DEVICES: APPLICATIONS AND MODELING - Bio-Inspired and Nanoscale Integrated Computing - page 50

[57, 58]. Similarly, the actuation mechanism in nanostructures is being studied
actively. For instance, electromechanical actuation in carbon nanotubes has been
demonstrated [59, 60] for applications such as artificial muscles.

2.4.3.3. Interconnect. One of the big challenges facing the integrated circuit
industry is the issue of interconnect. As devices shrink and are packed more
densely, routing the connections between them becomes more complicated; the
interconnect lines themselves can severely affect the operation speed and power
consumption of the circuit, to the point of becoming a limiting factor. Various
approaches are being pursued to address this problem. One solution is to make 3D
integrated circuits (as opposed to current planar or 2D circuits), which would
create more ways of connecting devices and make shorter paths possible [61]. So
far in this chapter we have been discussing the usage of nanomaterials to make
devices. It is noteworthy that several research groups are also working on the
possibility of using materials such as carbon nanotubes for interconnecting the
devices on a circuit [62, 63]. Since these materials can carry large current densities
and operate in the ballistic transport regime, this could lead to potentially faster
interconnects with less power consumption.

2.4.3.4. Hydrogen Storage. Alternative energy sources are becoming in-
creasingly important and research in this field is very active. Hydrogen-based
energy requires the storage of hydrogen in a safe and efficient manner. Carbon
nanotubes are being investigated for their potential in storing hydrogen in high
densities [64].

2.4.3.5. Optical Properties of Nanostructures. The focus of this chapter
has been mainly on the electronic properties of nanodevices. However, optical
properties are closely related to electronic properties; microscale optoelectronic
devices are in widespread use. Nanoscale optoelectronic devices are the subject of
active research. Examples include lasers based on nanowires [65] and optical
emitters [66, 67], detectors [68, 69], and antennas [70] based on carbon nanotubes.

2.5. MODELING AND SIMULATING NANODEVICES

2.5.1. The Art of Modeling
In the world of natural sciences and engineering, the art of modeling consists of
describing a physical system in terms of parts and phenomena that we can
understand based on our knowledge of nature, in the simplest possible manner, in
such a way that none of the fundamental aspects of its operation are lost, and that
we can use the model to predict/explain the results of experiments on the system.
The model often involves a number of mathematical equations that can be solved
to explain or to predict experimental outcomes. As a matter of fact, it could be
argued that the most fundamental

laws of nature, as we know them, are