Anyone likes to do proposal and presentation individually?

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Anyone likes to do proposal and presentation individually?

First and middle names

Group #

Last name

CHAVEZ

MCCUTCHEN

KENNEDY

PARKER

KRIEGER

SERBINOWSKI

BURTON

MAHMOOD

YAO

HONG

BASKARAN

THOMPSON

JOSE JACOB

JARED STEVEN

ASHLEY MARIE

MITCHELL DENNIS

ISAAC

KONRAD

RACHEL M

TAWSIF

YUE

JINHWAN

KARTHIKEYAN

BENJAMIN CLYDE

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1

1

2

2

2

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3

3

4

4

4

Lecture 15: Two special modes for AFM: Electrostatic Force Microscopy (EFM)
and Magnetic Force Microscopy (MFM)

• basic principles and mechanisms of EFM and MFM;

• two scanning modes;

• typical applications: with EFM for applications in interfacial charge

transfer and separation, and MFM for exploring the nanostructural

magnetic information’s (real case studies as inspired from mother

Nature).

EFM also called:
scanning electrostatic potential microscopy (SEPM)
(Force àfeedback; potential àmeasurement)

or Kelvin probe force microscopy (KPFM)

What is EFM?

o

o

o

o

EFM is a secondary imaging mode derived from AFM.

EFM measures electric field gradient distribution above the sample surface, through

measuring local electrostatic interaction between a conductive tip and a sample .

In EFM, a voltage is applied between the tip and the sample.

The bias is used to create and modulate an electrostatic field between the tip and the

substrate.

o

The cantilever(cid:1)s resonance frequency and phase change with the strength of the electric field

gradient and are used to construct the EFM image.

o

EFM can be used to distinguish conductive and insulating regions in a sample.

What are other secondary imaging modes derived from AFM?

Electrostatic Force Microscopy (EFM)

Electrostatic Interaction Upon Voltage Application

100 µm

25 µm

3 µm

20 nm

bias = 1 V

Tip apex

Cantilever

Tip cone

Cantilever frequency change due to electrostatic interaction

Phase Imaging

Two types of EFM measurement:

1. Lifted mode: constant height
l Because the electrostatic forces interact at greater distances than van der

Waals forces, so electrical force information can be separated from
surface topography simply by increseasing the tip-to-sample distance —
lift up the tip.

l Dual scanning — Grounded tip (no bias) first acquires surface topography

in the tapping mode, then the tip is lifted up (typically 5-50 nm), and
retraces the surface profile maintaining constant tip-surface separation.

l A constant voltage is maintained on the tip. As the tip moves over an

attractive electric field gradient, it is pulled toward the sample. When the
tip traverses a repulsive gradient, it is pushed away from the sample.
l The deflection (or frequency change) of the cantilever, proportional to the
charge density, can be measured using the standard light-lever system.