Applications of many beam systematic diffraction contrast in high voltage transmission electron microscopy

The increase in number of reflections that occurs as the voltage is increased above 100 to 650 kV leads to several new applications of contrast analysis and improved resolution. In systematic orientations two practical examples of contrast analysis are described. In the first, it is shown how the nature of stacking faults (intrinsic or extrinsic) can be found from the contrast of dark field images formed in 1 g when the 2 g systematic condition is satisfied. The contrast is high if the phase factor α = −2π/3 and considerably lower when α = +2π/3. This is a general method and does not have the limitations of current methods of analysis, unless defects are very small (≪ the extinction distance). In the second method further exploration is made of the improved resolution that can be obtained for diffraction contrast at defects such as dislocations by lowering the effective extinction distance, e.g. by dark field weak‐beam, or bright field high order reflection, imaging. These methods have been applied to defects in boron implanted silicon in which for the first time, dissociated loops have been resolved. From the separation of the partials, the stacking fault energy is estimated to be (45 ± 6) erg/cm 2 (isotropic elasticity) or (51 ± 7) erg/cm 2 (anisotropic elasticity theory).