Practical Electron Microscopy and Database

For any crystalline material, visibility criterion with g·b analysis can be used for dislocation characterization.

For instance, to determine whether the threading edge dislocation with a Burgers vector of a/2[1-10] in Si (silicon crystals) can be visible under specific diffraction conditions, we'll use the g·b criterion. This criterion states that a dislocation is visible in a TEM image when the dot product of the diffraction vector g and the Burgers vector b is non-zero (g·b ≠ 0). This can be done by calculating g·b for each of the given g vectors:

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  Therefore, for g = (200) case, g·b ≠ 0, so the dislocation will be visible.

• For g = (101) case:

  

  

  

  Therefore, for g = (101) case, g·b ≠ 0, so the dislocation will be visible.

• For g = (002) case:

  

  

  

  Therefore, for g = (002) case, g·b = 0, so the dislocation will not be visible.