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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