Van der Waals Epitaxy of Anatase TiO2 on mica and Its Application as Buffer Layer**Supported by the National Key Research and Development Program of China under Grant No 2016YFA0300102, the National Natural Science Foundation of China under Grant Nos 11675179, 11434009 and 11374010, and the Fundamental Research Funds for the Central Universities under Grant No WK2340000065.

Abstract

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 TiO2 thin films on mica substrates. Structural analyses reveal that the carefully chosen growth temperature (650°C) and suitable crystalline phase (anatase phase) of TiO2 are the key issues for this van der Waals epitaxy. Moreover, as a buffer layer, the TiO2 layer successfully suppresses the decomposition of BiFeO3 and the difficulty of epitaxial growth of BiFeO3 is decreased. Therefore, relatively high-quality anatase TiO2 is proved to be an effective buffer layer for fabricating more functional oxides on mica.