Electron backscatter diffraction and electron channeling contrast imaging of tilt and dislocations in nitride thin films

In this paper we describe the use of electron backscatter diffraction (EBSD) mapping and electron channeling contrast imaging---in the scanning electron microscope---to study tilt, atomic steps and dislocations in epitaxial $\mathrm{GaN}$ thin films. We show results from a series of $\mathrm{GaN}$ thin films of increasing thickness and from a just coalesced epitaxial laterally overgrown $\mathrm{GaN}$ thin film. From our results we deduce that EBSD may be used to measure orientation changes of the order of 0.02\ifmmode^\circ\else\textdegree\fi{}, in $\mathrm{GaN}$ thin films. As EBSD has a spatial resolution of $\ensuremath{\approx}20\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, this means we have a powerful technique with which to quantitatively map surface tilt. We also demonstrate that electron channeling contrast images may be used to image tilt, atomic steps, and threading dislocations in $\mathrm{GaN}$ thin films.