Development
Sergei Magonov, John Alexander, Sergey Belikov and Craig Wall
NT-MDT Development Inc., 430 W. Warner Rd., Tempe, AZ 85284, USA
New HD-AFM Mode; Your Path to Understanding
Forces for Precise Material Properties
Agenda
1. Introduction: Few Words about NT-MDT Microscopes
2. Basics of Hybrid Mode
3. Unexpectedly High-Contrast Visualization with Hybrid Mode
4. Comparing Forces in the Amplitude Modulation & Hybrid Modes
5. Mapping Stiffness and Adhesion: Towards True Quantitative Nanomechanical Analysis
6. Hybrid and Amplitude Modulation Modes in Concert
7. Summary
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Visualization
Compositional
Mapping
Nano-
Mechanical
Studies
Local
Electric/Magnetic
Studies
Atomic Force Microscopy @ Its Applications
Spectroscopy
Chemical
Identification
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Contact Mode Amplitude Modulation Mode
Scanner
wprobe
wprobe wdrive wscanner
wdrive
Hybrid Mode
Multi-
Channel
Analysis
Scanner
DC deflection
Deflection@wdrive
Amplitude, phase (wprobe)
Scanner
Scanning probe microscopes from NT-MDT
NEXT
High-Speed Acquisition and Processing
Module
enables Hybrid Mode and other innovative
capabilities
NTEGRA Key Features
Low Amplitude & High Voltage Noise
(25fm/Hz & 1mV/600V)
facilitate atomic-force resolution in AM mode
Industry-Leading Five Lock-in Amplifiers
provide multi-frequency electric, piezo-
response & mechanical studies in AM-
related modes
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18 nm
12 nm 12 nm
Height
Phase
NSG30 40N/m probe A0=1nm, Asp= 0.6 nm
Calcite (0.83 nm 0.51 nm)
Atomic- and Molecular Resolution in AM Mode
Imaging of TTF-TCNQ crystal & PTFE chains in air
10 nm
Height TTF-TCNQ
(1.2 nm 0.38 nm)
PTFE chains with
the inter-chain
distance of 0.56 nm
Height
9 nm
Height
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Imaging of a calcite crystal in water
TTF
Tetrathiafulvalene
TCNQ
tetracyanoquinodimethane
243 × 200 - sigmaaldrich.com
Single-Pass Kelvin Force Microscopy, dC/dZ, dC/dV Studies
S. Magonov and J. Alexander Beilstein Journal of Nanotechnology, 2011, 2, 15.
Parallel LIA Setting
In Series LIA Setting
Amplitude Modulation (AM)
Phase Modulation (PM)
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Advantages of Single-Pass KFM versus Double-Pass KFM
Tip-sample electrostatic force
1. Faster imaging 2. Superior sensitivity and spatial resolution
1 mm
Height Surface Potential dC/dZ
Height Surface potential Surface potential
1.6 mm 80 nm
Single-Pass KFM-PM of F14H20: Sensitivity & Resolution
Semifluorinated alkanes (F14H20) on Si
F14H20 on HOPG
0.60 nm
0.48 nm
- +
m=3.1D
CF3(CF2)14(CH2)20CH3
F14H20
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Basics of the Hybrid Mode
D
t
Temporal Deflection Plot – The Bank of the Local Properties!
1 cycle at 0.5 - 3.0 kHz
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H. Becker, et al “Stylus profiler featuring an
oscillating probe” US Patent 2728222, 1955.
V. Elings, & J. Gurley “Jumping probe
microscope” US Patent 5,229,606, 1993.
Predecessors
Real-time Wavelet Filtering
Pulsed Force (Witec), Jumping Mode
(NanoTech), Peak Force (Bruker), Anasys
Height Baseline
20 mm
Height
3 mm
V=0V Baseline V=6V Baseline
20 mm
Height Baseline
Hybrid mode images of Hard Disk Hybrid mode images of Zip Disk
Hybrid mode images of carbon nanotubes on Si
Sensing Long-Distant Forces in Hybrid Mode
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The baseline variations
reflect the variations of
the long-distance
magnetic and electric
forces.
3.5 mm
Height Stiffness Adhesion Current
Height Current
0.5 mm
Hybrid mode images of the carbon nanotubes on Si substrate
Current Imaging in Hybrid Mode
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The local current contrast is quite different
from the height profile and adhesion and
stiffness variations.
Unexpectedly High-Contrast Visualization with Hybrid Mode
Height
3 mm
Height Height
3 mm 3 mm
Height Height
1 mm 1 mm
LLDPE
LDPE
Amplitude Modulation Mode
Amplitude Modulation Mode
Hybrid Mode
Hybrid Mode
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Low force High force
700 nm
Height
300 nm
Height
700 nm
Height
300 nm
Height
Height
1 mm
1 mm
Height
Amplitude Modulation Mode
Amplitude Modulation Mode
Hybrid Mode
Hybrid Mode
PE-0.87
PE-0.86
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Unexpectedly High-Contrast Visualization with Hybrid Mode
1 mm
Height
1 mm
Height
Height Height
400 nm 400 nm
Linear Molecular Brushes
with Long Side Chains
Amplitude Modulation Mode Hybrid Mode
AM
HD
AM
HD
Height
Height
Amplitude Modulation Mode Hybrid Mode
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Unexpectedly High-Contrast Visualization with Hybrid Mode
Height Adhesion
300 nm 300 nm
Height Phase
Height Height Adhesion Phase
450 nm 450 nm
AM
AM
HD
HD
Linear and Star-Shaped Molecular
Brushes with Short Side Chains
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Unexpectedly High-Contrast Visualization with Hybrid Mode
HD AM HD AM
Comparing Forces in the AM & Hybrid Modes
AFM probe, w=50 kHz, k = 0.5 N/m, Q = 80, Rt =10 nm, A0 = 5 nm
65MPa
200MPa
600MPa
3GPa
7GPa
Samples
S. Belikov and S. Magonov Proceedings American
Control Conference, St. Louis, 979-985, 2009.
S. Belikov et al Fall 2012 MRS Proceedings, 2013, in press.
The tip-sample interactions in AM mode
were calculated by KBM asymptotic of
the Euler-Bernoulli equation with Hertz
model.
00
0
coscos2
cos
/sin
ydyyAZFkA
Q
AA
spcz
sp
0coscos2
1
2
0
2
00
A
AydyyAZF
kA
Q sp
spcz
csp ZARZRh max
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Estimation of force in Amplitude Modulation mode
Estimation of force in Hybrid mode
In the Hybrid mode (wdrive = 1.5 kHz), the force F = kD i.e. for the 0.5 N/m probe and 1 nm deflection, F = 500 pN,
for the 0.05 N/m probe and 1 nm deflection, F = 50 pN.
The minimal forces for the AM and HD modes are close yet
their action time (50kHz & 1.5 kHz) is quite different that
makes a difference for viscoelastic samples!
500 nm
Height
500 nm
Height
Height
500 nm
Height
500 nm
Adhesion
500 nm
Triblock copolymer (SBS)
film on Si (RT spin-casting)
Amplitude Modulation Mode Hybrid Mode
Amplitude Modulation Mode Hybrid Mode Triblock copolymer
(SBS) film on Si
(hot spin-casting)
S. N. Magonov, V. Elings, J. Cleveland,
D. Denley, and M.-H. Whangbo, Surface
Science 1997, 389, 201.
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Comparing Forces in the AM & Hybrid Modes: Theory
Soft top structure was correctly
represented in the low-force
images in the AM and HD modes.
Only the low-force
image in the AM mode
correctly represents the
surface topography. The
height contrast in the
HD mode is different
most likely due to local
adhesion variations. The AM mode might be superior than the HD
mode in the correct profiling of soft surfaces!
Height Phase
Height Adhesion Stiffness
3 mm
3 mm
Godovsky Yu., Papkov V.,
Magonov S. Macromolecules
2001, 34, 976.
Magonov S., Elings V.,
Papkov V. Polymer 1997,
38, 297.
Mapping Adhesion and Stiffness in Hybrid Mode
Amplitude Modulation Mode Images of Polydiethylsiloxane - PDES on Si
Hybrid Mode Images of Poly(diethylsiloxane) - PDES on Si
PDES is a mesomorphic
polymer, which consists of
cigar-like lamellar aggregates
embedded in amorphous
material.
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3 mm
Height Adhesion Stiffness
Height Adhesion Stiffness
3 mm
Mapping Adhesion and Stiffness in Hybrid Mode
4 mm
Height Adhesion Stiffness
Material Elastic Modulus
PBD 16MPa
PE 0.86 16MPa
LDPE 250MPa
PS 3.0GPa
Bi 32GPa
Sn 50GPa
PS
LDPE
PS
PBD
Components for
Binary Compositions
PE-0.86
PBD
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Towards True Quantitative Nanomechanical Analysis
Polymer
Material
Elastic Modulus
Macro
Elastic Modulus
AFM
Work of Adhesion
Macro
Work of Adhesion
AFM
PDMS-8 13.4MPa 13.9MPa 49 J/m2 32 J/m2
PDMS-60 1.61MPa 1.74MPa 58 J/m2 52.2 J/m2
PDMS-130 0.74MPa 0.66MPa 47–58 J/m2 42.1 J/m2
PDMS130
PDMS60 PDMS8 PDMS8
AFM-Based Quantitative Nanoindentation
Conservative Models: Hertz, Sneddon, JKR, DMT
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Rubbery Materials:
PDMS8, PDMS60 and PDMS 130
D D
Z Z PBD
PS
Deflection –versus-Distance (DvZ) Curves obtained in the Hybrid Mode on PS/PBD Blend
The elastic and viscoelastic
deformation of PS and PBD
locations do not allows their
true quantitative analysis with
the same elastic model!
JKR model was sued for calculations of elastic
moduli of PDMS samples from the force curves.
Height
10 mm
Height
Surface potential
Stiffness
10 mm
Hybrid Mode and Amplitude Modulation Mode in Concert
Hybrid Mode
Amplitude Modulation with Single-Pass KFM-PM
Bi
Bi
Sn
Sn
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A combination of a Hybrid Mode
with Amplitude Modulation mode
and related techniques achieved
in NT-MDT microscopes is a
basis for a comprehensive AFM
analysis of materials.
Studies of Bi/Sn Alloy
Height
Surface potential dC/dZ
1 mm
adhesion Adhesion Stiffness
Hybrid Mode and Amplitude Modulation Mode in Concert
Height
Height
Adhesion Stiffness
Surface potential
dC/dZ
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S. Belikov, J. Alexander, S. Magonov, and I.
Yermolenko, Amer. Control Conference 2012, 3228.
F14H20 on HOPG
Hybrid Mode
Amplitude Modulation
Mode/Single-Pass KFM
Despite on the overall similarity of the contrast in HD and AM
images, the cross-section profiles reveals specific features of the
adhesion, stiffness, surface potential and dC/dZ variations!
For calculation of dielectric
permittivity from dC/dZ see:
Summary
Hybrid mode offers advanced visualization of nanoscale structures, mapping of
long-distance tip-sample force interactions and local adhesive and stiffness
responses for a broad range of materials.
Further developments in recording of the time-dependent mechanical behavior
and dissipative deformation models will open the path to true quantitative
nanomechanical analysis.
Hybrid mode in concert with the Amplitude Modulation and related Single-Pass
techniques provides the grounds for comprehensive nanoscale analysis of
materials.
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Acknowledgements
Prof. M. Moeller (DWI, Aachen, Germany), Prof. S. Sheiko (UNC, Chapel Hill, NC), Prof.
Kuljanishvili (SLU, Saint Louis, MO), and Prof. V. Papkov (INEOS, Moscow) are cordially
thanked for providing the examined samples of semifluorinated alkanes, brush-like
macromolecules, carbon nanotubes and PDES polymer.
Dr. S. Leesment (NT-MDT, Zelenograd, Russia) is acknowledged for the data obtained on Bi/Sn
alloy.
My colleagues at NT-MDT Development Inc.: Dr. S. Belikov, Dr. C. Wall and J. Alexander are
thankful for the everyday support and for their help with the preparing the data and
presentation.
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