graphene ppt (2)

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GRAPHENE TRANSISTOR :

GRAPHENE TRANSISTOR PRESENTED BY, NAME: ARUN THOMAS ROLL NO: 12

CONTENTS:

Introduction MOSFET What is Graphene.? Graphene as a material. Graphene vs Silicon Properties. Fabrication of Graphene. Graphene Transistor. Advantage. Disadvantage. Application. Conclusion. Reference. CONTENTS

INTRODUCTION:

One of the major milestones in electronics was the discovery of transistor in 1948 by a team of physicists at the Bell Telephone Laboratories. Moor’s law. But the speed of integration is decreasing. Poor stability if size is below 10 nm. Graphene a material to replace silicon. INTRODUCTION

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A type of FET. Most commonly used type of silicon transistor. It is a four-terminal device with source (S), gate (G), drain (D), and body (B) terminals. When suitable current is applied at the gate current flows from source to drain. Two types are Enhancement MOSFET and depletion enhancement MOSFET MOSFET

WHAT IS GRAPHENE?:

Graphene is a flat monolayer of carbon atoms tightly packed into a two- dimensional (2D)honeycomb structure A form of carbon called graphene makes experiments possible that give new twist to electronics field. This devices are predicted to be substantially faster, thinner & more efficient than current silicon based devices. WHAT IS GRAPHENE?

GRAPHENE AS A MATERIAL:

Graphene as a material is completely new –not only the thinnest ever but also the strongest. It is the one-atom thick planar sheet of carbon atoms, which makes it the thinnest material ever discovered. Carbon atoms in the sheet are densely packed in a two-dimensional(2D) honeycomb crystal lattice. The carbon-carbon bond length in graphene is about 0.142nm. GRAPHENE AS A MATERIAL

GRAPHENE TO SILICON :

GRAPHENE TO SILICON Chemical Properties of Graphene & Silicon : Structure of Graphene & Silicon : Silicon bond Graphene is two dimensional allotrope of carbon , while silicon is single dimensional metalloid found in nature. Two-D Graphene

ELECTRICAL PROPERTIES OF GRAPHENE & SILICON :

Break-over voltage of graphene is less than 0.3V, & that of silicon is 0.3 Volts Graphene is a Zero Gap Semiconductor. So it has Electron transfer is 200 times faster than Silicon. On-off ratio Graphene has very small voltage gain Electrons in graphene move at an effective speed of light 300 times less than the speed of light in a vacuum ELECTRICAL PROPERTIES OF GRAPHENE & SILICON

GRAPHENE FABRICATION:

Laboratory method. Exfoliation Method. Using simple chemistry GRAPHENE FABRICATION Fig: Graphene Sheets in layer Fig: Single G raphene Sheet

GRAPHENE TRANSISTORS:

GRAPHENE TRANSISTORS

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Graphene exhibits a pronounced effect to perpendicular external electric fields, allowing us to build FETs. However, these graphene transistor show a very poor on-off ratio, small voltage gain but operating frequencies greater than 25GHz. Recently researchers have been able to create graphene transistors with an on-off ratio rate of 100GHz. IBM had developed 10000 top gated transistors on 0.24 centimeter square chip.

CONSTRUCTION:

Baking Silicon Carbide Drive off silicon atoms Lithographic Mask Introduction of Hydrogen gas CONSTRUCTION

ADVANTAGES:

100Ghz speed. Wide frequency range ADVANTAGES 1. HIGH FREQUENCY OPERATION 2. SELF COOLING 3. WORKING WITHOUT MUCH NOISE

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IT HAS THE ABILITY TO OPERATE WITH AS LITTLE AS THREE VOLTS CONSUME VIRTUALLY NO POWER WIDE TEMPERATURE RANGE IMMUNITY TO RADIATION SUPERB ELECTRON & HEAT CONDUCTIVITY, GREATER THAN COPPER. Cond …

DISADVANTAGES:

A way to deposit graphene on large scale instead of small pieces is still needed to be developed. Difficulty to turn off. Single sheet of graphene is hard to produce. Due to small voltage gain, practical use is limited. DISADVANTAGES

APPLICATIONS:

Can be used to make anti bacterial materials as well as bio devices. Can be used in communication systems. Military applications. Medical applications. Can be used in nano robots. APPLICATIONS

CONCLUSION:

Graphene is a material which has the capability to eliminate the current semiconductors such as silicon and form a new era of superfast micro electronics. High speed transistors can be expected in the near future. Challenges. Future. CONCLUSION

REFERENCE :

http://www.bit-tech.net http://dailyreckoning.com http://www.zdnet.com http://www.extremetech.com http://www.nature.com http://www.technologyreview.com REFERENCE

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