Epitaxial (0001) ZnO Films obtained by Magnetron Sputtering on C-Sapphire Substrates with a WO2 + x Buffer Nanolayer

For structural and geometric matching of the crystal lattices of the (0001) Al2O3 substrate and the deposited ZnO films, it is proposed to use a nanometer-thick WO2+x buffer layer. Using the method of reactive magnetron sputtering, an initial nanolayer of amorphous tungsten oxide is deposited on c-sapphire, which, during solid-phase annealing in oxygen at a pressure of 1.33 Pa and a substrate temperature of 650 °C, goes through a series of structural changes associated with changes in the composition of the WO2+x film. As the parameter x increases, processes of modification of the substrate surface occur and, at a certain stage, conditions are created for the epitaxial growth of the ZnO film. The structural features of the films were studied by reflection high-energy electron diffraction.