Beam broadening in transmission and conventional EBSD

Transmission electron backscatter diffraction (t-EBSD) has become a routine technique for crystal orientation mapping when ultrahigh resolution is needed and has demonstrated advantages in the characterization of nanoscale and micron-sized samples (Babinsky et al., 2015). In this work, we use experimental measurements and simulations to compare the resolution of the transmission and conventional reflection EBSD techniques across a range of sample volumes and characterization conditions. Monte Carlo simulations of electron trajectories provide the opportunity to estimate beam size and effective resolution, as well as electron flux, as a function of sample thickness or incident beam energy in t-EBSD. Increasing incident beam energy is shown to negatively impact beam diameter in some cases, and the effect of thinning a sample for conventional EBSD is shown to improve characterization resolution but dramatically decrease the number of high-loss electrons backscattered to the detector. In addition to considering spatial resolution when implementing EBSD techniques, it is found that maintaining a high yield of diffracted electrons to the detector is also of critical importance, which is supported by experimental results. Consequently, this work provides key insights into the nature of electron scattering and probe volume for the practical implementation of both transmission and reflection EBSD techniques.