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Nanocomputing is an emerging technology that is at the early stage of its development.It is the technology in which computing is done by using  extremly small, or nanoscale, devices.

Nanocomputing shows great potential, but there are significant technical barriers and obstacles to overcome. Worldwide initiatives are in progress to develop the technology. Japan, Europe, and the United States are in a race to the finish line. Governments are beginning to see the potential and are investing heavily in research and development programs. This interest and investment will accelerate progress.

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l Computing with nanoscale devices

  • Ø 1nm = 10-3 µm = width of 10 H atoms = diameter of sugar molecule
  • Ø 1011- 1012 devices/cm2
  • Ø 100– 1000 billion-device chips
  • Ø 1 – 50 nanometer device features

(Source:ITRS)

Until the mid-1990s, the term “nanoscale” generally denoted circuit features smaller than 100 nm. As the IC industry started to build commercial devices at such size scales since the beginning of the 2000s, the term “nanocomputing” has been reserved for device features well below 50 nm to even the size of individual molecules, which are only a few nm. . In 2001, state-of-the-art electronic devices could be as small as about 100 nm, which is about the same size as a virus. Scientists and engineers are only beginning to conceive new ways to approach computing using extremely small devices and individual molecules.

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All computers must operate by basic physical processes. Contemporary digital computers use currents and voltages in tens of millions of complementary metal oxide semiconductor (CMOS) transistors covering a few square centimeters of silicon. If device dimensions could be scaled down by a factor of 10 or even 100, then circuit functionality would increase 100 to 10,000 times. Today’s transistors operate with microampere currents and only a few thousand electrons generating the signals, but as they are scaled down, fewer electrons are available to create the large voltage swings required of them. This compels scientists and engineers to seek new physical phenomena that will allow information processing to occur using other mechanisms than those currently employed for transistor action.

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Note  : CMOS device circa 2016

•Cost 10-11$/gate

•Size 8 nm / device

•Speed 0.2 p s /operation

•Energy 10-18J/operation

Future nanocomputers could be evolutionary, scaled-down versions of today’s computers, working in essentially the same ways and with similar but nanoscale devices. Or they may be revolutionary, being based on some new device or molecular structure not yet developed. Current nanocomputing research involves the study of very small electronic devices and molecules, their fabrication, and architectures that can benefit from their inherent electrical properties.  Nanostructures that have been studied include semiconductor quantum dots, single electron structures, and various molecules. Very small particles of material confine electrons in ways that large ones do not, so that the quantum mechanical nature of the electrons becomes important.

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Notes:

v CMOS scaling will continue for next 12 –15 years

v Alternative new technologies will emerge and begin to be integrated on CMOS by 2015

v Nanoscience research is needed to facilitate radical new scalable technologies beyond 2020

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Quantum dots behave like artificial atoms and molecules in that the electrons inside of them can have only certain values of energy, which can be used to represent logic information robustly. Another area is that of “single electron devices,” which, as the name implies, represent information by the behavior of only one, single electron. The ultimate scaled-down electronic devices are individual molecules on the size scale of a nm. Chemists can synthesize molecules easily and in large quantities; these can be made to act as switches or charge containers of almost any desirable shape and size. One molecule that has attracted considerable interest is that of the common deoxyribonucleic acid (DNA), best known from biology. Ideas for attaching smaller molecules, called “functional groups,” to the moleculesand creating larger arrays of DNA for computing are under investigation. These are but a few of the many approaches being considered.

As the size of computer chips gets smaller and smaller, companies continue to invest research dollars to reduce the size. The near future of nanocomputing could bring powerful computers that are smaller than the head of a pin.

In addition to discovering new devices on the nanoscale, it is critically important to devise new ways to interconnect these devices for useful applications. One potential architecture is called cellular neural networks (CNN) in which devices are connected to neighbors, and as inputs are provided at the edge, the interconnects cause a change in the devices to sweep like a wave across the array, providing an output at the other edge.

An extension of the CNN concept is that of quantum-dot cellular automata (QCA). This architecture uses arrangements of single electrons that communicate with each other by Coulomb repulsion over large arrays.

Emerging Research Architectures

ARCHITECTURE

3-D INTEGRATION

QUANTUM CELLULAR AUTOMATA

DEFECT TOLERANT ARCHITECTURE

MOLECULAR ARCHITECTURE

CELLULAR NONLINEAR NETWORKS

QUANTUM COMPUTING DEVICE IMPLEMENTATION

DEVICE IMPLEMENTATION

CMOS with dissimilar material systems

Arrays of quantum dots

Intelligently assembles nanodevices

Molecular switches and memories

Single electron array architectures

Spin resonance

ADVANTAGES

Less interconnect delay, Enables mixed technology solutions

High functional density. No interconnects in signal path

Supports hardware with defect densities >50%

Supports memory based computing

Enables utilization of single electron devices at room temperature

Exponential performance scaling, Enables unbreakable cryptography

CHALLENGES

Heat removal, No design tools, Difficult test and measurement

Limited fan out, Dimensional control (low temperature operation), Sensitive to background charge

Requires pre-computing test

Limited functionality

Subject to background noise, Tight tolerances

Extreme application limitation, Extreme technology

MATURITY

Demonstration

Demonstration

Demonstration

Concept

Demonstration

Concept

Another potential architecture is that of “crossbar switching” in which molecules are placed at the intersections of nanometer-scale wires. These molecules provide coupling between the wires and provide computing functionality.

In summary, nanocomputing technology has the potential for revolutionizing the way that computers are used. However, in order to achieve this goal, major progress in device technology, computer architectures, and IC processing must first be accomplished. It may take decades before revolutionary nanocomputi ng technology becomes commercially feasible.

A nanocomputer is similar in many respects to the modern personal computer—but on a scale that’s very much smaller. With access to several thousand (or millions) of nanocomputers, depending on your needs or requirements—gives a whole new meaning to the expression “unlimited computing”—you may be able to gain a lot more power for less money.

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Nanocomputing is evolving along two distinct paths:

New nanoproducts, techniques, and enhancements will be integrated into current technology such as the PC, the mainframe, and servers of all types. Mass storage will change significantly as thousands of cheap storage devices will become available. Storage need never be a problem or cost again.

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Research and development are working toward making entirely new nanocomputers that run software—similar to that on today’s PC.

REFERENCE:

http://www.mitre.org/research/nanotech

intelcorp.georg/dourianoff

fortes@us/.edu

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