The Electron Microscopy Center

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Scanning electron microscopy (SEM)

Description

Scanning Electron Microscopy (SEM) utilizes an electron probe that is scanned accross the sample producing secondary and back-scattered electrons that can be detected and recorded as an image. The penetration depth is generally less that one micron, so the images produced are of the sample surface. The backscattering of electrons increases with increasing atomic number, so that imaging with this method can produce images of heavier elements. On the SEM’s available resolution can range from several microns down to 1nm.

Sample Types and Preparation

Thin films, powders, fibers, bulk materials,

Instrumentation

MODEL S-3200-N HITACHI SCANNING ELECTRON MICROSCOPE

  • Filament Type: Tungsten hairpin
  • Image Resolution: Secondary Electron = 3.5 nm
  • Back-scattered Electron = 5.5 nm
  • Specimen Stage: Movement range = 80 mm x 40 mm
  • Tilt angle = -20 o to + 90 o
  • Rotation angle = 360 o
  • Specimen Mounts: Hitachi Aluminum 15mm with M4 thread
  • Hitachi Aluminum 25mm with M4 thread
  • 1 1/4″ diameter mounted samples
  • Sample Size: 31.5 mm maximum diameter
  • 10 mm maximum height (larger samples may be accommodated depending on the geometry of the sample)

MODEL S-900 HITACHI SCANNING ELECTRON MICROSCOPE

  • Filament Type: Cold-cathode field emission
  • Image Resolution: Secondary Electron = 1.0 nm
  • Specimen Stage: Movement range = 7 mm x 4 mm
  • Tilt angle = + 40 o to – 40 o
  • Specimen Mounts: Special mount that accepts a sample that is:
  • Sample Size: No larger than 4 mm x 8 mm x 1.9 mm

MODEL S-4300 HITACHI SCANNING ELECTRON MICROSCOPE

  • Filament Type: Cold-cathode field emission
  • Image Resolution: Secondary Electron = 1.5 nm
  • Specimen Stage: Movement range = 50 mm x 100 mm
  • Tilt angle = – 5 o to + 60 o
  • Rotation = 360 o – continuous
  • Specimen Mounts: Hitachi Aluminum 15mm with M4 thread
  • Hitachi Aluminum 25mm with M4 thread
  • Maximum Specimen Size: 102 mm in diameter
  • Maximum Specimen Height 19 mm (including specimen mount)
  • Auxiliary attachments include:
    • (a) Princeton Gamma-Tech EDS Microanalysis system
    • (b) Oxford HKL EBSD system

Advantages

Generally the sample prep required is minimal. SEM use can be learned fairly quickly.

Limitations

Samples must be dry and not sensitive to the electron beam. Imaging of wet samples can be attempted in the environmental SEM S-3200.

Examples