Novel TiO(2)/ZnO multilayer mirrors at 'water-window' wavelengths fabricated by atomic layer epitaxy

We propose that novel oxide superlattice structures of crystalline TiO(2)/ZnO on sapphire substrates can be used for multilayer mirrors with high reflectivity at 2.734 nm. In the experimental study, both rutile TiO(2)(200) and wurtzite ZnO(001) thin films were grown epitaxially on the same sapphire (001) substrate by atomic layer epitaxy (ALE) at 450 °C. We also demonstrated that the novel oxide superlattice structure of 10-bilayer TiO(2)/ZnO on a sapphire substrate gave a high reflectivity of 29.4% at 2.74 nm.