Van der Waals epitaxy and remote epitaxy of LiNbO₃ thin films by pulsed laser deposition

Nonlinear oxides such as LiNbO₃ have found many applications in both conventional electro-optics and quantum optics. In this work, we demonstrate the van der Waals and remote epitaxy of LiNbO₃ films on muscovite mica and graphene-buffered sapphire, respectively, by pulsed laser deposition. Structural analysis shows that the epitaxial relation in van der Waals epitaxy is LiNbO₃ (0001) || mica (001) and LiNbO₃ [011¯0] || mica [010] with LiNbO₃ [101¯0] || mica [010], a 60°-rotated twin structure. The relation in remote epitaxy is LiNbO₃ (0001) || sapphire (0001) and LiNbO₃ [011¯0] || sapphire [011¯0] with twin structure LiNbO₃ [1¯010] || sapphire [011¯0]. Furthermore, in remote epitaxy, Raman scattering analysis confirms the existence of graphene after deposition. Finally, we find that the oxygen partial pressure influences the presence of impurity phases significantly. The successful demonstration of van der Waals and remote epitaxy promises the feasibility of developing thin film LiNbO₃ on demanded substrates toward scalable electro-optics.