Van der Waals Epitaxy of Anatase TiO_2 on mica and Its Application as Buffer Layer

MICAtronics, based on the functional oxide/mica heterostructures, has recently attracted much attention due to its potential applications in transparent, flexible electronics and devices. However, the weak van der Waals interaction decreases the tolerable lattice mismatch and thus limits the species of function oxides that are able to be epitaxially grown on mica. We successfully fabricate relatively high-quality epitaxial anatase TiO_2 thin films on mica substrates. Structural analyses reveal that the carefully chosen growth temperature (650^\circ\!C) and suitable crystalline phase (anatase phase) of TiO_2 are the key issues for this van der Waals epitaxy. Moreover, as a buffer layer, the TiO_2 layer successfully suppresses the decomposition of BiFeO_3 and the difficulty of epitaxial growth of BiFeO_3 is decreased. Therefore, relatively high-quality anatase TiO_2 is proved to be an effective buffer layer for fabricating more functional oxides on mica.