Introduction to Sensing Probe Microscopy (SPM) Outline

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Introduction to Sensing Probe Microscopy
(SPM)Outline

• Laboratory safety issues
• The word of nanotechnology
• Terminology
• What is SPM?

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Laboratory Safety Review

• Laser
• High Voltages
• Piezo Scanner Precautions

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Laser Safety Information

• This system is designed to be used with a class
  II diode laser with an output of up to 1 mW of
  visible radiation at 670 nm.
• DO NOT stare directly into the laser beam.
• WARNING Use of controls or adjustments or
  performance of procedures other than those
  specified herein may result in hazardous light
  exposure. Furthermore, the use of optical
  instruments with this product may increase eye
  hazard.

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High Voltages

• High voltages are present in the instrument.
  Never open the boxes for servicing or adjustments
  before disconnecting the AC line cords.

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Piezo Scanner Precautions

• Piezo scanners are very FRAGILE pieces of
  equipment. The piezo material that does the
  scanning is a ceramic and is consequently quite
  easily broken. Dropping a piezo scanner will
  result in damage to the scanner that can only be
  repaired by completely replacing the scanner
  piezo core. This can be an expensive and
  time-consuming process and so it is advised that
  the utmost care is used when handling the
  scanners.
• Agilent Technologies, Inc. recommends that the
  scanners be stored in the padded scanner case
  that was supplied with the scanner and that the
  scanner be kept in a dry environment when not in
  use. Piezo scanners also perform better with
  consistent use. If a scanner is not used for some
  time it may require a short period of use before
  the scan range is stable and the calibration is
  correct. It may also be necessary to recalibrate
  the scanner from time to time.

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The World of Nano-technology
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The world of nanotechnology

• http//www.kqed.org/quest/television/fullscreen?id
  189
• http//www.nanowerk.com/nanotechnology/videos/Atom
  ic_force_microscopy_at_the_Gerton_Lab.php

2-D and 3-d view of a polymer under studies at
SJSU
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Terminology
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Scanning Probe Microscopy (SPM)Terminology

• Atomic Force Microscopy (AFM)
• Contact mode
• Non contact mode/Acoustic AC Mode (AAC mode)
• Phase Imaging
• Lateral Force Microscopy (LFM)
• Scanning Tunneling Microscopy (STM)
• Magnetic Force Microscopy (MFM)
• Electric Force Microscopy (EFM)
• Force Modulation AFM
• Current Sensing AFM (CSAFM)

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What is Scanning Probe Microscopy?
a family of tools for the nanotechnology world..
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What is SPM?A Family of Microscopes
Scanning Probe Microscopy (SPM) (air, liquid,
vacuum)
AFM
Contact Modes Topography LFM,
SThM Lithography
Scanning Tunneling Microscopy (STM)
Topography Spectroscopy Lithography
EChem. BEEM
AC Modes Topography MFM, EFM
SKPM Others
Electro Chemistry
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Focusing on Atomic Probe Microscopy

• Scanning Probe Microscopy
• Measuring the current between tip and surface
• AFM Atomic Force Microscopy
• Contact direct interaction with surface
• Non Contact cantilever vibrates above the
  surface
• LFM Lateral Force Microscopy
• Forces (frictional) on lateral movement measured
• MFM Magnetic Force Microscopy
• Surface magnetic field imaged
• And many other techniques.

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Scanning Tunneling Microscopy (STM)
Measuring the current between tip and surface
Requires a conductive surface
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Frictional ForceLateral Force Microscopy
Low Friction
Low Friction
High Friction
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Lateral Force Microscopy (LFM)
Image of Mixed Self-assembled Monolayer in
contact mode, in solution )
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Magnetic Force Microscopy
Magnetic domains on a 5 Gb hard disk A)
Topographic image in close contact mode B) Phase
image after increasing the set point of the same
area in A. Both images are 40x40 µm2.
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Electrical TestCurrent Sensing AFM
Electrical TestI/V
Attach electrical test equipment to the probe and
make point by point measurements on a surface.
Current
Voltage
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Scratching
When Scratching With the AFM, there is a torsion
on the cantilever so the probe area changes.
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AFM Nanoindenting

1. The AFM probe is pushed into the sample to cause
   an indentation
2. The applied force is calculated from the
   cantilever mechanics
3. The AFM sensor measure the probe motion under the
   applied force
4. Cantilever stiffness must be matched to the
   hardness of the sample.

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AFM Nanoindenting
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Electric Force Microscopy
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Hierarchy of Measurements
Optical
Profilometry
SEM
AFM
TEM
10 mm
10 mm
10 nm
varying length scale
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SEM Comparison

• SEM
• - Good Depth of field
• - Fast scanning
• 2D magnification
• Need ultra vacuum
• Surface has to conduct

• AFM
• Limited depth of field
• Contrast on Flat Samples
• - 3D Magnification
• Works in vacuum, ambient air and in liquids

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Elements of a Basic Atomic force Microscope
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AFM Simulation
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Interaction between Tip and Sample

• Scanning a sharp tip mounted on a cantilever
  across an object surface
• Measuring the forces between tip and surface

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Potential Diagram
Repulsive Cantilever pushed up
Distance
Potential
AttractiveCantilever pulled down
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Continuous - Contact
Contact Point
Potential
Distance
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Vibrating Mode
Potential
Distance

• The tip is vibrated in and out of the potential
  associated with the surface.- Large or small
  amplitudes- Advantages are low forces, reduced
  lateral forces

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SPM Applications

• Life Sciences
• Cells, Bio-molecules, Biomaterials
• Material Sciences
• Semiconductors, Ceramics, Polymers
• High Technology
• Data Storage, Optics, Semiconductors, Biotech.
• Low Technology
• Paper, Steel, Plastics, Automobile