2d nano-electromechanical materials: recent...
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2D Nano-Electromechanical Materials: Recent Highlights
Karel-Alexander Duerloo*, Yao Li, Dr. Mitchell Ong, Prof. Evan Reed (PI)
Recent highlights 1. We discover piezoelectric 2D materials
• Building blocks of 2D sensor and filter devices 2. We discover accessible phase
transitions in 2D materials • Information and energy storage in 2D
materials
3D Materials vs. 2D Materials
108 atoms
108 a
tom
s
108 atoms
few atoms thick
Normal (3D) material Two-dimensional (2D) material
not naturally occurring, but can be synthesized
Advantages of 2D materials: 1. Ultra-lightweight; 2. Ultra-flexible, wearable; 3. Very strong (up to 20% strain); 4. Low power requirements; 5. Good and diverse electronic properties; 6. Can be combined via stacking.
2010 Nobel Prize in Physics
graphite graphene
Many different 2D materials exist:
Graphene (C) BN
MoS2 MoSe2 MoTe2 WS2
WSe2
WTe2 TaS2
TaSe2 TaTe2 NbS2
NbSe2 NbTe2
In2Se3 InSe HfS2 …
Which have the most useful properties for electronic devices and sensors? Our HPC efforts provide
direction.
Recent highlights 1. We discover piezoelectric 2D materials
• Building blocks of 2D sensor and filter devices 2. We discover accessible phase
transitions in 2D materials • Information and energy storage in 2D
materials
Piezoelectricity Defined Coupling between mechanical stress and electrical polarization.
_ + + _
Most engineering materials do not have this property.
Applications for Piezoelectricity 1. Impact or Pressure sensors 2. Vibration sensors 3. Generation/detection of sonar waves 4. Nanometer-precision motors and actuators 5. Surface Acoustic Wave (SAW) signal filters 6. Electricity generation 7. In-service detection of propagating cracks
a SAW filter (used in every
cellphone)
Can 2D materials be applied in this context?
Computational Prediction of 2D Piezoelectricity
quantum mechanical simulations
HPC
2D Piezoelectricity
Graphene (C) BN
MoS2 MoSe2 MoTe2 WS2
WSe2
WTe2 TaS2 TaSe2 TaTe2 NbS2
NbSe2 NbTe2
In2Se3 InSe HfS2 …
Calculated d11 coefficients (pm/V):
0
2
4
6
8
10
12
AlN
α-quartz
ZnO
BN MoS2 MoSe2 MoTe2 WS2 WSe2 WTe2
Duerloo, J. Phys. Chem. Lett., 3, 19 (2012)
Our HPC-enabled approach enables identification of promising materials.
Applications for Piezoelectricity 1. Impact or Pressure sensors 2. Vibration sensors 3. Generation/detection of sonar waves 4. Nanometer-precision motors and actuators 5. Surface Acoustic Wave (SAW) signal filters 6. Electricity generation 7. In-service detection of propagating cracks
a SAW filter (used in every
cellphone)
Can 2D materials be applied in this context? yes
0 0.005 0.01 0.015 0.020
1
2
3
4x 10
!17
Strain !11
! !22
Qm
eta
l (C
)
0 2 4 6 8 10 120
0.005
0.01
0.015
0.02
Str
ain
!11 !
!22
Time (s)
0 2 4 6 8 10 12!0.01
!0.005
0
0.005
0.01
Curr
ent (p
A)
Time (s)
Our HPC-enabled predictions have driven experimental observation
Confirmed in experiments at Columbia U. ARL has parallel efforts.
Leveraged Piezoelectricity in Ultra-Thin Bilayers
Duerloo, Nano Lett., 13, 1681-1686 (2013)
Recent highlights 1. We discover piezoelectric 2D materials
• Building blocks of 2D sensor and filter devices 2. We discover accessible phase
transitions in 2D materials • Information and energy storage in 2D
materials
Some materials have more than one 2D crystal structure:
2H
1T
1T’
semiconductor
metal
metal
Semiconducting Metallic
Two phases have been observed in chemically exfoliated monolayer
MoS2 and WS2.
Eda et al, ACS Nano 6, 7311 (2012); Voiry et al, Nat. Mat. (2013).
Can the phases of monolayers be engineered and employed in devices?
Metallic
Some materials have more than one 2D crystal structure:
2H
1T’
semiconductor
metal
Can this phase transition be controlled in an electronic device? If so: which material is most promising?
HPC challenge: find phase-changing materials
MoS2 WS2
MoSe2 WSe2
MoTe2 WTe2
2D p
hase
ene
rgy
(e
V p
er M
X2)
Our semi-local DFT calculations indicate MoTe2 and WTe2 exhibit the smallest
2H-1T’ energy difference.
PBE EXC. No phonons.
Discovery: tension causes phase transition
x-axis extension (%)
y-ax
is e
xten
sion
(%)
Lesson from HPC-enabled screening: 1) Use MoTe2; 2) Apply tension along the
crystal’s y-axis.
HPC bypasses trial-and-error steps and guides future experiments.
Duerloo will be visiting ARL in July for a week to participate in this ARL experiment with Madan Dubey et al.
x-axis extension (%)
y-ax
is e
xten
sion
(%)
In-depth HPC calculations on Garnet show temperature brings 2D phase transition even
closer to ambient conditions.
MoTe2, PBE, 300 K
x-axis extension (%) y-
axis
ext
ensi
on (%
) MoTe2, HSE06, 300 K
2
0
6
4
10
8
0 4 8 -4
2
0
6
4
0 2 4 -2
Recent highlights 1. We discover piezoelectric 2D materials
• Building blocks of 2D sensor and filter devices 2. We discover accessible phase
transitions in 2D materials • Information and energy storage in 2D
materials
Strain engineering of electrical contacts with monolayers
Phase transitions in monolayer TMDs
Experiments being done at ARL (Madan Dubey,
Matt Chin, et al) to study impact of piezoelectricity
on electrical contacts under strain.
ARMY COLLABORATIONS ON FLEXIBLE ELECTRONICS
ARL experiments (Dubey et al.) with flexible
substrates to observe metal transitions in MoTe2.
Upcoming ARL visits: • Duerloo visits for a week in
July to participate in experiment
• Reed visits in July
HIVE Data Visualization
data provided by Yao Li
PROJECT PUBLICATIONS FY 2013
Recent journal publications: • Duerloo, K.-A. N., Li, Y., Reed, E. J., “Structural Phase Transitions in Two-
Dimensional Mo and W-Dichalcogenide Monolayers,” Nature Communications, in press (2014).
• Duerloo, K.-A. N., Reed, E. J., “Flexural Electromechanical Coupling: a Nanoscale Emergent Property of Boron Nitride Bilayers,” Nano Letters, 13, 1681-1686, doi:10.1021/nl4001635 (2013).
• Ong, M. T., Duerloo, K.-A. N., Reed, E. J., “The Effect of Hydrogen and Fluorine Coadsorption on the Piezoelectric Properties of Graphene. Journal of Physical Chemistry C,” 117, 3615-3620, doi:10.1021/jp3112759 (2013).
Recent Army visits: ARL (Nov. 2012), Picatinny (Dec. 2012), Natick (Jan. 2013), ARL (May 2013, February Feb. 2014). ARL Adelphi and Aberdeen upcoming in July 2014.
2D Nano-Electromechanical Materials Karel-Alexander Duerloo*, Yao Li,
Dr. Mitchell Ong, Prof. Evan Reed (PI)