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MOLECULAR ELECTRONICS

What is MoletronicsWhat is Moletronics

• It is interdisciplinary theme that spans Physics , Chemistry & Material science.

• Special feature is the use of molecular building block for fabrication of electronic component in both active and passive form.

• It is such field of nanoscience ,that evolves with the exploration of the electronic level structure , response & transport for development of electronic devices.

• As there is binding of molecular building block it forms larger structure and show dynamical stereochemistry.

History• Robert muliken & Albert Szent-Gyorgi proposed

study of charge transfer theory in1940.• In 1974 Mark Ratner & Avi Aviram illustrated a

theoratical molecular rectifier.• Later Avi Aviram detailed a single molecular field

effect transistor in1988.• In 2000Shirakawa, Heeger and MacDiarmid won

Noble prize in physics for potentially high conductivity of (oxidised) polyacetelene & it’subsequent development.

About Molecular ElectronicsAbout Molecular Electronics

• The principle of above research is that biological systems can give useful paradigm for developing electronic and computational devices at the molecular level.

• The approach involves the design and synthesis of dyads, triads and other super molecular species using the techniques of organic chemistry.

• In order to studied newly prepared molecule time resolved laser spectroscopy, NMR spectroscopy.

Why molecular electronicsWhy molecular electronics

• For electronic application, molecular structures has four major advantages:

• Size.

• Assembly & Recognition.

• Dynamical stereochemistry.

• Synthetic tailor ability.

FigureFigureBuckminister Fullerene

Rotating view of Buckminister Fullerene C60 crystal

Moore’s lawMoore’s law• The number of transistors that can be fabricated

on a silicon integrated circuit--and therefore the computing speed of such a circuit--is doubling every 18 to 24 months.

• After four decades, solid-state microelectronics has advanced to the point at which 100 million transistors, with feature size measuring 180 nm can be put onto a few square centimeters of silicon.

Electrode effectElectrode effect• The molecule electrode interface limit current

flow & completely modify the measured electrical response of the junction.

• Poor covalent bonding exists between molecule and electrode.

• A related consideration involves how chemical nature of molecule-electrode affects the rest of the molcule

Molecule Electronics Molecule Electronics CircuitsCircuits

• The proposed circuit architectures have attempted to deal with five key issues:

• Tolerance to manufacturing defects.• Introduction to non-traditional fabrication

methods.• scalability to near molecular dimensions.• Briding between device densities.• Fabrication symplicity.

Some Molecular Electronics Some Molecular Electronics CircuitCircuit

FEDs SETs

Crossbars & DemultiplexersCrossbars & Demultiplexers

• The most attractive architectures for designing molecular-electronics circuits for computational applications and interfacing them to the macroscopic world is the crossbar.

• The memory, shown on the right, consists of two major components. The central crossbar—the crossing of16 vertical and 16 horizontal black wires—constitutes a 256-bit memory circuit.

Figure of Crossbars and Figure of Crossbars and DemultiplexersDemultiplexers

Crossbars and Demultiplexers

AdvantagesAdvantages• Tiny.

• Low power consumption.

• Able to integrate large circuit

• Re-configurable.

DisadvantagesDisadvantages

• Controlled fabrication with in specified tolerances.

• Hard experimental verification.

ApplicationApplication• Sensors.

• Displays, Energy transduction devices.

• Smart Material, Molecular scale transistors.

• Molecular Motors, Logic and memory devices.

ConclusionConclusion• Molecular systems, or systems based on small

organic molecules, possess interesting and useful electronic properties.

• The investigations of molecular systems that have been performed in the past have been strongly influenced.

• The potential application of molecular electronics has already attracted the interest of some large corporate.