Epitaxial growth and orientation of AlN thin films on Si(001) substrates deposited by reactive magnetron sputtering

Epitaxial domain formation and textured growth in AlN thin films deposited on Si(001) substrates by reactive magnetron sputtering was studied by transmission electron microscopy and x-ray diffraction. The films have a wurtzite type structure with a crystallographic orientation relationship to the silicon substrate of AlN(0001)‖Si(001). The AlN film is observed to nucleate randomly on the Si surface and grows three dimensionally, forming columnar domains. The in-plane orientation reveals four domains with their a axes rotated by 15° with respect to each other: AlN⟨112¯0⟩‖Si[110], AlN⟨011¯0⟩‖Si[110], AlN⟨112¯0⟩‖Si[100], and AlN⟨011¯0⟩‖Si[100] An explanation of the growth mode based on the large lattice mismatch and the topology of the substrate surface is proposed.