The aim of the project is to establish a method to directly extract the sample thickness from the size of the Kikuchi diffraction pattern direct beam.
The broader perspective is to develop a data analysis code which can automatically extract the diameter of the primary beam in all the Kikuchi patterns of a scanned map, transform it in a relative thickness value and plot a 2D thickness variation map as a result.
The envisioned work includes:
- Learning the use of focused ion beam (FIB) and ion milling for the fabrication of samples with a well-known thickness profile, to be used as calibration samples for the thickness measurement scheme;
- Determination of the primary beam profile in TKD patterns collected in vacuum;
- Calculation of the expected oversaturated area vs. thickness trend, its range of validity, and linearity;
- Analysis of different materials, in view of compiling a library of the measurable thickness range as a function of atomic number;
- Comparison of the extracted thickness with measurements obtained independently by Electron Energy Loss Spectroscopy (EELS) and/or Convergent Beam Electron Diffraction (CBED).