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NANO TECHNOLOGY
Definition
It is any technology, which exploits phenomena, and structures that can only occur at the nanometer
scale, which is the scale of several atoms and small molecules. Nanotechnology is the understanding
and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena
enable novel applications.
Overview
The related term nanoscience is used to describe the interdisciplinary fields of science devoted to
the study of nanoscale phenomena employed in nanotechnology. This is the world of atoms,
molecules, macromolecules, quantum dots, and macromolecular assemblies, and is dominated by
surface effects such as Van der Waals force attraction, hydrogen bonding, electronic charge, ionic
bonding, covalent bonding, hydrophobicity, hydrophilicity, and quantum mechanical tunneling, to
the virtual exclusion of macro-scale effects such as turbulence and inertia. For example, the vastly
increased ratio of surface area to volume opens new possibilities in surface-based science, such as
catalysis.Nanotechnologies may provide new solutions for the millions of people in developing
countries who lack access to basic services, such as safe water, reliable energy, health care, and
education. The United Nations has set Millennium Development Goals for meeting these needs. The
2004 UN Task Force on Science, Technology and Innovation noted that some of the advantages of
nanotechnology include production using little labor, land, or maintenance, high productivity, low
cost, and modest requirements for materials and energy.
Many developing countries, for example Costa Rica, Chile, Bangladesh, Thailand, and Malaysia, are
investing considerable resources in research and development of nanotechnologies. Emerging
economies such as Brazil, China, Inia and South Africa are spending millions of US dollars annually on
R&D, and are rapidly increasing their scientific tt ademonstrated by their increasing numbers of
publications in peer-reviewed scientific publications.
Introduction
The top-down approach anticipates nanodevices that must be built piece by piece in stages, much as
manufactured items are currently made. Scanning probe microscopy is an important technique both
for characterization and synthesis of nanomaterials. Atomic force microscopes and scanning
tunneling microscopes can be used to look at surfaces and to move atoms around. By designing
different tips for these microscopes, they can be used for carving out structures on surfaces and to
help guide self-assembling structures. Atoms can be moved around on a surface with scanning probe
microscopy techniques, but it is cumbersome, expensive and very time-consuming. For these
reasons, it is not feasible to construct nanoscaled devices atom by atom. Assembling a billion
transistor microchip at the rate of about one transistor an hour is inefficient. However, these
techniques may eventually be used to make primitive nanomachines, which in turn can be used to
make more sophisticated nanomachines.
In contrast, bottom-up techniques build or grow larger structures atom by atom or molecule by
molecule. These techniques include chemical synthesis, self-assembly and positional assembly.
Another variation of the bottom-up approach is molecular beam epitaxy or MBE. Researchers at Bell
Telephone Laboratories like John R. Arthur. Alfred Y. Cho, and Art C. Gossard developed and
implemented MBE as a research tool in the late 1960s and 1970s. Samples made by MBE were key
to to the discovery of the fractional quantum Hall effect for which the 1998 Nobel Prize in Physics
was awarded. MBE allows scientists to lay down atomically-precise layers of atoms and, in the
process, build up complex structures. Important for research on semiconductors, MBE is also widely
used to make samples and devices for the newly emerging field of spintronics.