Nanocircuits are electrical circuits on the scale of nanometers. One nanometer is equal to 10-9 meters or a row of 10 hydrogen atoms. With circuits becoming smaller, there is an ability to fit more on a computer chip. This allows more complex functions using less power and at a faster speed. Nanocircuits are organized into three different parts: transistors, interconnections, and architecture, all dealt with on the nano scale.
Nanocircuitry
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Various Approaches to Nanocircuitry
A variety of proposals have been made to implement nanocircuitry in different forms. These includeSingle-Electron Transistors, Quantum dot cellular automata, and Nanoscale Crossbar Latches. However, likely nearer-term approaches will involve incorporation of nanomaterials to improve MOSFETs. These currently form the basis of most analog and digital circuit designs, the scaling of which drives Moore's Law. A review article[1] covering the MOSFET design and its future was published in 2004 comparing different geometries of MOSFETs under scale reduction and noted that circular cross-section vertical channel FETs are optimal for scale reduction. This configuration is capable of being implemented with a high density using vertical semiconductor cylindrical channels with nanoscale diameters and Infineon Technologies and Samsung have begun research and development in this direction resulting in some basic patents[2][3] using nanowires and carbon nanotubes in MOSFET designs. In an alternative approach[4], Nanosys is a new company using solution based deposition and alignment processes to pattern pre-fabricated arrays of nanowires on a substrate to serve as a lateral channel of an FET. While not capable of the same scalability as single nanowire FETs, the use of pre-fabricated multiple nanowires for the channel increases reliability and reduces production costs since large volume printing processes may be used to deposit the nanowires at a lower temperature than conventional fabrication procedures. In addition, due to the lower temperature deposition a wider variety of materials such as polymers may be used as the carrier substrate for the transistors opening the door to flexible electronic applications such as electronic paper, bendable flat panel displays, and wide area solar cells.
Production Methods
One of the most fundamental concepts to understanding nanocircuits is the formulation of Moore’s Law. This concept arose when Intel co-founder Gordon Moore became interested in the cost of transistors and trying to fit more onto one chip. It relates that the number of transistors that can be fabricated on a silicon integrated circuit—and therefore the computing abilities of such a circuit—is doubling every 18 to 24 months.[5] The more transistors one can fit on a circuit, the more computational abilities the computer will have. This is why scientists and engineers are working together to produce these nanocircuits so millions and perhaps even billions of transistors will be able to fit onto a chip.
Potential Applications and Breakthroughs
Scientists in India have recently developed the world’s smallest transistor which will be used for nanocircuits. The transistor is made entirely from carbon nanotubes. Nanotubes are rolled up sheets of carbon atoms and are more than a thousand times thinner than human hair.[12]Normally circuits use silicon-based transistors, but these will soon replace those. The transistor has two different branches that meet at a single point, hence giving it a Y shape. Current can flow throughout both branches and is controlled by a third branch that turns the voltage on or off. This new breakthrough can now allow for nanocircuits to hold completely to their name as they can be made entirely from nanotubes. Before this discovery, logic circuits used nanotubes, but needed metal gates to be able to control the flow of electrical current.
Economic Impact
With the vast improvements in reducing the size of circuits, comes a rising cost to produce these nano components. Scientists believe that one day a fabrication facility for making nanocircuit could cost as much as over $200 billion. The increased cost comes from the difficulty of producing such circuits as they take more time and effort than circuits today. The fabrication plant will create a raw nanocircuit—billions on billions of devices and wires whose functioning is rather limited. From the outside it will look like a lump of material with a handful of wires sticking out.[15] Eventually the theory of Moore’s Law will have to reach equilibrium with the fabrication methods currently used. Circuits will only be able to be so fast and small without creating any severe problems. The cost for producing even better nanocircuits will increase further as more money will be needed to develop new fabrication methods and ways of designing faster, better nanocircuits. Until that time, companies like Intel will continue to thrive in the nano business with their promises of their chip being the fastest and better than their counterpart. Nanocircuits may still have their problems, but that will not stop companies from mass producing them in order to become the most technologically advanced company with the fastest product.
Cellular automata
A cellular automaton (CA) is a finite state machine consisting of a uniform (finite or infinite) grid of cells. Each one of these cells can only be in one of a finite number of states at a discrete time. The state of each cell in this grid is determined by the state of its adjacent cells, also called the cell's "neighborhood." The most popular example of a cellular automaton was presented by John Horton Conway in 1970, which he named "The Game of Life."