Local Strain Distribution in AlN Thick Films Analyzed by X-Ray Microdiffraction

We investigated local strain distribution in a cross-sectional area throughout the thickness of a thick aluminum nitride (AlN) film epitaxially grown on a trench-patterned AlN/α-Al2O3 template using X-ray microdiffraction measurements for AlN and Bragg reflections. The results show that the presence of voids caused by the trench pattern strongly influences on the distribution of the strain components in the and directions, which are perpendicular to the trench lines. Discrepancy between strain values obtained from the two Bragg reflections was shown to be the result of twisting of the crystal domains about the axis in the thick AlN film.