Structure and symmetry of multicrystal thin films grown on single crystal templates

This paper describes the use of crystalline templates to grow heteroepitaxial thin films with highly textured microstructures approximating general polycrystalline films. The underlying crystallographic principles are reviewed. While bicrystals are described by two-color symmetries, higher order polycrystals generate new symmetry elements given by the different permutations of colors. Experimental results are presented that illuminate these principles with practical examples of thin film microstructures in different materials, using transmission electron microscopy for microstructural and crystallographic analysis.