Effects of accelerating voltage and specimen thickness on the spatial resolution of transmission electron backscatter diffraction in Cu.

A quantitative approach was proposed to determine the spatial resolution of transmission electron backscatter diffraction (t-EBSD) and to understand the limits of spatial resolution of t-EBSD. In this approach, Cu bicrystals and digital image correlation were employed. The effects of accelerating voltage and specimen thickness on the spatial resolution of t-EBSD were also investigated. t-EBSD specimens with 8μm×10μm dimensions and different thicknesses were prepared using focused ion beam milling. The optimized quality of Kikuchi pattern was achieved at a working distance of 12mm and a tilting angle of 20°. The optimum depth resolution of 34.4nm was observed in the lower surface of a 100nm thick sample at 25kV. Thus, the penetration depth from the upper surface is 65.6nm. The optimum lateral and longitudinal resolutions obtained from a 100nm thick sample at 30kV are 25.2 and 43.4nm, respectively. The spatial resolution of t-EBSD can be enhanced by increasing the accelerating voltage and decreasing the sample thickness.