Study on the influence of different trench-patterned templates on the crystalline microstructure of AlN epitaxial films by X-ray microdiffraction

The crystalline microstructure of AlN films epitaxially grown on trench-patterned templates of AlN/α-Al2O3 and α-Al2O3 was studied by position-dependent X-ray microdiffraction measurements of AlN and 0004 Bragg reflections. The crystalline microstructure of the AlN films is highly anisotropic and periodic corresponding to the periodicity in the trench pattern of templates. The lattice tilting fluctuation in the AlN film grown on the trench-patterned α-Al2O3 template is about one-half order of magnitude larger than that in the AlN film grown on the trench-patterned AlN/α-Al2O3 template. This is likely to be related to the significant misorientation initiated at the growth of AlN crystal domains from the sidewalls of the α-Al2O3 template without AlN buffer layers and the difference in contact areas at the AlN film/α-Al2O3 interface between the two samples. These findings suggest that trench-patterned templates of AlN/α-Al2O3 are suitable for growing thick high-quality AlN films.