Table 1227. Comparison of techniques of thickness determination of TEM/STEM samples.
Technique |
Practical measurable thickness and limitation |
Accuracy |
Principle |
|
100 - 500 nm, Crystalline only |
< 2 % |
Based on the variation of the intensity of the diffracted beam with thickness known as ‘Pendellösung’ fringes |
Two beam diffraction |
Crystalline only |
|
Count the extinction fringes under two beam diffraction contrast conditions. |
|
Crystalline only |
|
Percentage of the intensity of diffracted spots at specific crystalline orientation |
|
Crystalline only |
|
Use the intensity of electron diffraction and Kikuchi lines |
|
Crystalline only |
|
Based on extinction distance |
|
Crystalline and amorphous |
~10 % |
Electron scattering, measuring the incident and transmitted intensities in the same image |
|
Crystalline and amorphous |
~ 15-20 % if no calibration is done |
The intensity ratio between the plasma peaks and the zero loss peak provides the thickness information |
|
Crystalline and amorphous |
|
Employ a known planar feature, such as a slip trace, precipitate, or stacking fault |
|
Crystalline and amorphous |
|
Focus the beam finely so that contamination points at the top and at the bottom are formed. And then, the sample tilted to measure the geometry |