AFM University Introduction to Atomic Force Microscopy by Paul West

« Cover
« Foreward
« Chapter 1
 « Chapter 2
 « Chapter 3
 « Chapter 4
 « Chapter 5
 « Chapter 6
 
6.1 Probe Artifacts
6.1.1 Features on a Surface Appear Too Large
6.1.2 Features in an Image Appear Too Small
6.1.3 Strangely Shaped Objects
6.1.4 Repeating Strange Patterns in an Image
6.2 Scanner Artifacts
6.2.1 Probe / Sample Angle
6.2.2 X-Y Calibration / Linearity
6.2.3 Z Calibration / Linearity
6.2.4 Background Bow / Tilt
6.2.5 Z Edge Overshoot
6.2.6 Scanner Drift
6.2.7 X-Y Angle Measurements
6.2.8 Z Angle Measurements
6.3 Image Processing
6.3.1 Leveling
6.3.2 Low Pass Filter
6.3.3 Matrix Filter / Smoothing
6.3.4 Fourier Filtering
6.3.5 Image Looks Too Good
6.4 Vibrations
6.4.1 Floor Vibrations
6.4.2 Acoustic Vibrations
6.5 Other Sources
6.5.1 Surface Contamination
6.5.2 Electronics
6.5.3 Vacuum Leaks
6.5.4 PID Settings / Scan Rate
6.5.5 Laser Interference Patterns
 « Chapter 7
« Appendix A
« Appendix B
« Appendix C
« Appendix D
About
Downloads
Home


Chapter 6
next » index « back

Common artifacts are:

  • Features on a surface appear too large
  • Features in an image appear too small
  • Strangely shaped objects
  • Repeating strange patterns in an image
6.1.1 Features on a Surface Appear Too Large
Often the size of features on the surface such as nanotubes or nanospheres look larger than expected. However, the height of the feature when measured by a line profile is correct.
FIGURE 6-1 Motion of an AFM probe as it goes over a sphere that is attached to a surface. In such a measurement the side of the probe will cause a broadening of features in the image.
FIGURE 6-2 A-B: 400 × 400 nm AFM image of an 8 nm diameter sphere. A: The line profi le of the image shows a diameter of 92 nm and a height of 8 nm. B: The broadening in the image is caused by the shape of the probe used for measuring this AFM image.
6.1.2 Features in an Image Appear Too Small
If the probe needs to go into a feature that is below the surface, the size of the feature can appear too small. The line profile in these cases is established by the geometry of the probe and not the geometry of the sample. However, it is still possible to measure the opening of the hole from this type of image. Also, the pitch of repeating patterns can be accurately measured with probes that don't reach the bottom of the features being imaged.

next » « back
  111