On-Line Measurement of Foil Thickness from Convergent Beam Electron Diffraction Patterns

Abstract

Accurate values of foil thickness are required in many materials science applications, such as for measurement of defect concentrations and for x-ray microanalysis absorption corrections. Kelly et al. demonstrated that convergent beam electron diffraction (CBED) patterns can be analyzed using a simple graphical technique to give values for foil thickness with ±2% accuracy. More recently, Allen extended the treatment to make use of both maxima and minima in the CBED disks. The technique requires a knowledge of the d-spacing of the reflection, the electron wavelength, an evaluation of the deviation parameter, si, associated with the i-th fringe in the diffracted beam disk, and the assignment of a set of constants to "index" the fringes.