Scanning Electron Microscopy (SEM)

Scanning electron microscopy (SEM) is an electron microscopy technique in which a tiny beam of electrons is scanned across the surface of a sample. A high-resolution 3D image of the sample surface is generated when the electron beam strikes a metal-coated specimen and the electrons reflected (back-scattered) or given-off (secondary electrons) are detected.


Hitachi S4700 SEM (Ultrahigh resolution SEM with field-emission gun)

Hitachi S2600 SEM (Environmental/low vacuum variable pressure SEM)

Tousimis Critical Point Dryer and Cressington Sputter Coater to prepare samples for Hitachi S4700 SEM

Sample Preparation:

Hitachi S2600 – samples are not required to be dehydrated and coated

Hitachi S4700 – samples are required to be dehydrated and coated

  1. Fixation
  2. Dehydration
  3. Critical point dry (complete dehydration)
  4. Mounting
  5. Sputter coating (with Gold and/or Platinum)
  6. SEM

Comparison of S4700 and S2600

Hitachi S4700 Field emission (FE)-SEMHitachi S2600 Variable pressure (VP)-SEM
ResolutionUltrahigh up to 2 nmRelatively high up to 5 nm
Electron GunField emission cold gun
- very bright, tiny spot size, low voltage
Tungsten thermionic gun
- less accurate beam spot
VacuumUltrahighLow, variable setting (1 – 270 Pa)
Sample ConditionDry, coated with metalWet sample can be viewed
No sample preparation is needed


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