Transmission and Scanning Transmission Electron Microscopy (Imaging)

Conventional Transmission Electron Microscopy (CTEM)

TEM brightfield image of Ni grains in thin film
Grain size distribution extracted from the brightfield image

Basis:

  • Mass thickness and mainly diffraction contrast for bright- and darkfield imaging in the fixed beam mode

Possibilities:

  • Analysis of morphology of thin films including grain size distribution on the nanoscale
  • In-situ observation of crystallisation during heat treatment
  • Investigation of lattice defects in crystals

Electron Diffraction (ED)

TEM darkfield image of a thin annealed Ni-Fe layer with nBED pattern from the marked grain indexed with fcc structure in [111] zone axis

Basis:

  • Interferences of electron waves at crystal lattices

Modes:

  • Selected Area Electron Diffraction (SAED)
  • Nano Beam Electron Diffraction (nBED)
  • Convergent Beam Electron Diffraction (CBED)

Possibilities:

  • Phase analysis with correlations to morphological features on the sub-micrometer scale (SAED, nBED)
  • Texture analysis (SAED)
  • In situ observation of phase formation during annealing (SAED, nBED)
  • Determination of lattice parameters with high accuracy on the sub-micrometer scale (CBED)

High Resolution Transmission Electron Microscopy (HRTEM)

Basis:

  • Phase contrast due to the phase modulation of the electron waves by the periodic crystal lattice


Possibilities:

  • Characterisation of interfaces on the atomic scale
  • Visualization of nanocrystals in an amorphous matrix

Scanning Transmission Electron Microscopy (STEM)

Basis:

  • Mass thickness and diffraction contrast for brightfield imaging in the scanning mode
  • Dominant Z-contrast for distinction of different materials in High Angle Annular Darkfield (HAADF) imaging

Possibilities:

  • Material localization down to the sub-nanometer scale
  • Analysis of interfaces down to the sub-nanometer scale
  • Combined with EEELS and EDXS: chemical analysis with spatial resolution on the nanometer scale