TEM NBD (nanobeam diffraction) is the most favorable technique for routine strain analysis due to simple experimental set-up, nano-meter spatial resolution and high measurement sensitivity (std. dev. ~ 0.1%). However, for strain measurements, NBD is normally performed in STEM line-scanning mode and thus strain mapping over large sample area can be time-consuming.
When the NBD technique is operated in scanning mode, then it can be used to map strain across the specimen and record the diffraction
patterns directly on a two-dimensional (2D) detector for each probe position.
The recorded NBD patterns contain contributions from both elastic and inelastically scattered electrons. The sharpnes of NBD signal can be significantly improved by selecting the elastic scattering with an energy filter.
Characteristics of strain measurement using NBD:
i) Using NBD (as well as CBED) in TEM mode to obtain strain distribution is not convenient because the data are acquired manually,
ii) The quality of the NBD data depends to a great extent on the operator’s skill.