Smart Electronic Materials

1
Smart Electronic Materials

• Prof. A. Grishin
• Nanopiezotronics for Sensor and Generator
  Applications
• Jolien Dendooven
• Ezio Iacocca
• Nicolas Innocenti
• Filip Vanlerberghe

2
Nanopiezotronics

• Nano a word we love!
• -tronics suffix to make it sounds nicer
• Piezo stuff we deal with now

3
Direct piezoelectric effect

• Definition ability of some materials to generate
  an electric potential in response to applied
  mechanical stress.

Ref. 1
4
A question of structure

• Centrosymmetry

• Non-centrosymmetry

Ref. 2
5
Converse piezoelectric effect
Ref. 1
6
A link between two worlds

• Electricity electrical displacement
• D e E
• Solid mechanics Hooke's law
• S s T
• Piezoelectric material both laws are coupled!
• D dT T e E
• S s T d E
• d new parameter piezoelectrical constant

7
Which material?

• In nature
• - Quartz gt Watches!
• - Topaz
• - Cane sugar
• - Bones
• Human-made
• - some crystals
• - even some polymers
• - but mainly ceramics
• in particular ZnO

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ZnO piezoelectric?
Charges ? Zn2 O2-
OK! Structure ? Comes in two different types
of crystal Blende Wurtzite
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Blende
10
Blende
11
Wurtzite
Structure OK!
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Piezoelectrical ceramic and more...

• ZnO
• Bandgap 3.37 eV gt Semiconductor
• 3.37 eV --gt 328 nm, UV light
• gt Transparent at visible wavelengths
• Compatible with optical technologies

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More and more...

• Other uses of ZnO
• Antiseptic to cure eczema and skin injuries
• Contraindications "Do no ingest"
• gt Biocompatibility
• May be used in biological and medical
  applications

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Principle of nanopiezotronics
Ref. 4
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ZnO the perfect material

• Today's technology Silicon
• Onchip technology limited to electrical-electrical
  interactions
• Tomorrow's technology
• - broader interactions on chip
• - optoelectronics
• - biotechnologies
• ZnO - key for onchip silicon-mechanics
  interactions
• - compatible with optoelectronics
• - compatible with biotechnologies
• and even more...

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Nanostructures of ZnO

• ZnO can be grown in diverse structures
• Nanobelts, nanorings, nanospirals and nanohelices
• Patterned growth of aligned nanowires

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Nanobelts vapor-solid process
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Nanorings and nanospirals
Ref. 5
19
Superlattice-structured nanohelix
Superelasticity !
Ref. 7
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Patterned growth of aligned nanowires

• Important for applications
• Vapor liquid solid process

Ref. 8
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Patterned growth of aligned nanowires

• Random growth

• Patterned growth

Ref. 9
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Ideal growth conditions

• The growth direction is controlled by the
  epitaxial relationship between the substrate and
  nanowires.
• Nanowires grown on a silicon substrate are always
  randomly orientated because the gold catalyst
  tends to form an alloy with silicon and destroys
  the single-crystalline substrate surface.
• Because of a small lattice mismatch between the
  Al2O3 substrate and the gold particles, the
  substrate remains single-crystalline and orient
  the nanowires vertically.
• The aligning quality is controlled by
• the chamber pressure
• the oxygen partial pressure
• the thickness of the catalyst layer.

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Configuration for the applications

• A pattern of aligned nanowires
• for the generator
• A single nanowire
• for the PE-FET and the diode
• A single nanobelt
• for the bulk acoustic resonator

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Nanogenerator Principles

• Piezoelectric effect
• Stress ? electric field/potential distribution

Ref. 10
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Nanowire contacts

• Bottom ohmic contact
• work function lt electron affinity of ZnO
• Top Contact Schottky diode
• work function gt electron affinity of ZnO

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Potential build up and discharge made possible by
the Schottky barrier
Ref. 10
27
Direct current nanogenerator driven by ultrasonic
waves

• AFM tip replaced by zigzag electrode
• Vertically alligned array of ZnO NW

Ref. 11
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Different configuration possibilities of the NW
in respect to the zigzag electrode
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Equivalent electrical circuit and experimental
results
Ref. 11
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MOSFET
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PE-FETPiezoelectronic FET
Device overview
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PE-FETPiezoelectronic FET
Effects in the NW
Ref. 7
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Sensor Application

• Mobile electrode
• NanoNewtons measure

Ref. 7
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Piezoelectronic Diode
Ref. 7
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Piezoelectronic Diode

• Ohmic contact
• Zener-like behavior
• 6.6uA reverse current at -5V.

Ref. 7
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SAW and BAR
SAW BAR
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NB BAR device
Ref. 7
38
References

• 1 Piezooptics, http//www.bostonpiezooptics.com/
  .
• 2 Zhong Lin Wang, Nanopiezotronics, Advanced
  Materials, , no. 19, pp. 889892, 2007.
• 3 Biam, a French database of medicines for
  pharmacist and doctors, http//www.biam2.
• org/www/Sub1731.html.
• 4 Zhong Lin Wang, Electrostatic Potential in a
  Bent Piezoelectric Nanowire. The Fundamental
• Theory of Nanogenerator and Nanopiezotronics,
  Nano Letter, vol. 7, no. 8,
• 2007.
• 5 Zhong Lin Wang, Nanostructures of zinc oxide,
  Materialstoday, pp. 2633, June 2004.
• 6 Zhong Lin Wang, Piezoelectric Nanostructures
  From Growth Phenomena to Electric
• Generators, MRS Bulletin, vol. 32, pp. 109116,
  February 2007.
• 7 Zhong Lin Wang, The new eld of
  nanopiezotronics, Materialstoday, vol. 10, no. 5,
  pp.
• 2028, May 2007.
• 8 Nanowire photonics, http//www.nanowirephotoni
  cs.com/research-nanowires.
• html.
• 9 Xudong Wang, Jinhui Song, and Zhong Lin Wang,
  Nanowire and nanobelt arrays of zinc
• oxide from synthesis to properties and to novel
  devices, Journal of Materials Chemistry,

39
References (2)

• vol. 17, pp. 711720, 2007.
• 10 Z.L. Wang and J.H. Song, Piezoelectric
  Nanogenerators Based on Zinc Oxide Nanowire
• Arrays, Science, pp. 242246, April 2006.
• 11 X.D. Wang, J.H. Song, J. Liu, and Z.L. Wang,
  Direct-current nanogenerator driven by
• ultrasonic waves, Science, vol. 316, pp. 102105,
  2007.
• 12 Marc-Alexandre Dubois, Thin lm bulk acoustic
  wave resonators a technology
• overview, MEMSWAVE 03, July 2003.
• 13 Zinc-oxide, http//www.wikipedia.org/.
• 14 Jean-Pierre Gaspart, Introduction to
  Condensed Matter Physics, University of Liège.
• 15 John Toon, Superlattice Nanobelts, Research
  horizonts, 2005.
• 16 Zheng Wei Pan, Zu Rong Dai, and Zhong Lin
  Wang, Nanobelts of semiconducting
• oxides, Sience, vol. 291, pp. 19471949, March
  2001.
• 17 Z.L. Wang, Piezoelectric nanogenerators -
  their principle and potential applications,
• Physics, vol. 35, pp. 897903, 2006.
• 18 X.D. Wang, J. Liu, J.H. Song, and Z.L. Wang,
  Integrated nanogenerators in biouid,
• Nano Letters, vol. 7, pp. 24752479, 2007.
• 19 Professor Zhong LinWang's Nano Research
  Group, http//www.nanoscience.gatech.
• edu/zlwang/.