Coherently Scattering Domain Size vs. Grain Size in Thin Metallic Films: A Comparative Study by X-Ray Diffraction and Transmission Electron Microscopy

Grazing incidence x-ray diffraction (GID) and transmission electron microscopy (TEM) were used in a comparative investigation of nanometric Cu and W thin films. In the GID study, the in-plane grain size and microstrain present in the films were determined using established x-ray diffraction peak profile analysis. These results were compared to the TEM investigation in which hollow cone dark field (HCDF) imaging, conical dark field (CDF) imaging and precession electron diffraction (PED) were used to determine grain size. The spatial variation of crystallographic orientation within the films obtained via PED was used to determine the intragrain misorientations. For highly strained grains differences between the GID and TEM analysis are observed and are attributed to large intra-grain misorientations due to microstrain arising from lattice rotations resulting from the presence of dislocations. The combination of both characterization techniques on a common set of samples allowed for a quantitative review of Ungar's modified Williamson-Hall analysis: An additional broadening term, proportional to the product of microstrain and grain size broadening, is proposed.