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tpalacios@mit.edu

New Applications for Graphene Electronics New Applications for Graphene Electronics

Han Wang, Daniel Nezich, Jing Kong and Tomas Palacios

Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology tpalacios@mit.edu

This work is sponsored by MIT/Army Institute For Soldier Nanotechnologies (ISN) and the Interconnect Focus Center (SRC/FCRP IFC).

tpalacios@mit.edu

What is the best application for graphene?

• Electron mobility?

− µgraphene = 200,000 cm2/Vs

• Carrier velocity?
• ve,GNT = 5×107 cm/s
• Ballistic transport?

0.1 1 10 100 1 2 3 4 5 6 7

CNT

InSb GaN

GaAs

InP Si InAs

Electron velocity (10

7 cm/s)

Electric field (kV/cm)

CNT

InGaAsP

µInSb = 80,000 cm2/Vs Transport properties are not what make this material unique…

3

Unique properties of graphene

• Ambipolar transport with very high

mobility

• Bandgap control through etching

lateral bandgap engineering

• Flexible and transparent material
• Excellent electrostatic control

+

• Improved transport properties.
• 1

1 2 3 0.0 200.0 400.0 600.0 800.0 1.0m

Id (A) Vg (V) Graph F W1R7C01 THfO2 = 40nm W=5µm, L=10µm VDS = 1 V

e- h+

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Holes Electrons

New graphene devices: Frequency doublers

• Full wave rectification using a single graphene device
• No bandgap required
• Field effect transistor: Signal amplification possible
• Much higher efficiency than conventional diode or FET frequency doublers

h e

Graphene Ambipolar FET

Input signal (f0) Output signal (2f0)

Vp(Dirac Voltage)

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Fabrication of Graphene Frequency Multipliers

Final Device Optical Interference Image of graphene flakes Schematic Structure

• H. Wang, D. Nezich, J. Kong, and T. Palacios “Graphene Frequency

Multipliers” IEEE Electron Device Letters, May 2009..

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Output Input

• First demonstration of frequency

doubling

• Excellent spectral purity high

conversion efficiency

• High frequency operation
• Large gain possible
• No bandgap required

Experimental results… Graphene frequency doubler

Graphene is the an excellent material for high performance frequency multipliers

100 1000 0.1 1 10 100

FET frequency multipliers

Efficiency (%) Frequency (GHz)

x2 x2x2 x3 x2x2x2 x2x2x3 x2x2x2x2

Graphene frequency multiplier

Diode frequency multipliers

?

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Conclusion and Future Work

• Ambipolar frequency multipliers based on graphene demonstrated.
• Excellent spectral purity with 94% of the output power at useful frequency.
• No filtering elements are needed at the output.
• Signal amplification possible.

Many other new devices/applications are possible :

• Analog to digital converters
• Energy harvesting devices
• Advanced photodetectors
• …

Many other new devices/applications are possible :

• Analog to digital converters
• Energy harvesting devices
• Advanced photodetectors
• …
• H. Wang, D. Nezich, J. Kong, and T. Palacios, IEEE Electron Device Letters, May 2009.

tpalacios@mit.edu

tpalacios@mit.edu

Ambipolar Frequency Multipliers

Ambipolar Frequency Multipliers Conventional FET Frequency Multipliers I I-

• V Characteristics

V Characteristics Circuit and Output Waveform Circuit and Output Waveform Output Power Spectrum Output Power Spectrum I I-

• V Characteristics

V Characteristics Circuit and Output Waveform Circuit and Output Waveform Output Power Spectrum Output Power Spectrum

f f

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Why is spectral purity so high at the output?

Parabolic component of Ids-Vgs much larger in fabricated GFETs Less higher order harmonics, hence higher spectrum purity Sub-linear Ids-Vgs characteristics in fabricated GFETs

78% maximum 94%