ABSTRACT
Keywords: nanoscale, carbon nanotubes, bionanotechnology, lithography, molecular electronics, miniaturisation, atomic force microscope, scanning probe microscope, scanning tunnelling microscopy, fullerenes, spintronics 1.1 The Development of Nanoscale Science
The prefix nano comes from the Greek word for dwarf, and hence nanoscience (the commonly used term nowadays for nanoscale science) deals with the study of atoms, molecules and nanoscale particles, in a world that is measured in nanometres (billionths of a metre or 10−9, see Section 1.2). The development of nanoscience can be traced to the time of the Greeks and Democritus in 5th cen tury B.C., when people thought that matter could be broken down to an indestructible basic component of matter, which scientists now call atoms. Scientists have since discovered the
whole peri odic table of different atoms (elements) along with their many isotopes. The 20th century A.D. saw the birth of nuclear and particle physics that brought the discoveries of sub-atomic par ticles, entities that are even smaller than atoms, including quarks, leptons, etc. But these are well below the nanometre length scale and therefore not included in the history of nanoscale science and technology.The beginnings and developments of nanotechnology, the application of nanoscience, are unclear. The first nanotechnologists may have been medieval glass workers using medieval forges, although the glaziers naturally did not understand why what they did to gold made so many different colours. The process of nanofabrication, specifically in the production of gold nanodots, was used by Victorian and medieval churches which are famed for their beautiful stained glass windows. The same process is used for various glazes found on ancient, antique glazes. The colour in these antiques depends on their nanoscale characteristics that are quite unlike microscale characteristics.The modern origins of nanotechnology are commonly attri buted to Nobelist Dr. Richard Feynman, who on December 29, 1959, at the annual meeting of the American Physical Society at Caltech, delivered his now classic talk “There’s Plenty of Room at the Bottom” [1]. He described the possibility of putting a tiny “mechanical surgeon” inside the blood vessel that could locate and do corrective localized surgery. He also highlighted a number of interesting problems that arise due to miniaturisation since “all things do not simply scale down in proportion”. Nanoscale materials stick together by molecular van der Waals attractions. Atoms also do not behave like classical objects, for they satisfy the laws of quantum mechanics. He said, “... as we go down and fiddle around with the atoms down there, we are working with different laws, and we can expect to do different things.” Feynman said he was inspired by biological phenomena in which “chemical forces are used in repetitious fashion to produce all kinds of weird effects (one of which is the author)”. He predicted that the principles of physics should allow the possibility of manoeuvring things atom by atom.Feynman described such atomic scale fabrication as a bottom-up approach, as opposed to the top-down approach that is
commonly used in manufacturing, for example in silicon integrated circuit (IC) fabrication whereby tiny transistors are built up and con nected in complex circuits starting from a bare silicon wafer. Such top-down methods in wafer fabrication involve processes such as thin film deposition, lithography (patterning by light using masks), etching, and so on. Using such methods, we have been able to fabricate a remarkable variety of electronics devices and machinery. However, even though we can fabricate feature sizes below 100 nanometres using this approach, the ultimate sizes at which we can make these devices are severely limited by the physical laws governing these techniques, such as the wavelength of light and etch reaction chemistry.
