Oxide nanosheets tailoring thin film orientation

Abstract

Realizing high-quality epitaxial transition metal oxide thin films on Si, glass or arbitrary substrates is promising to offer novel features and high performance for devices in electronics, optoelectronics, sensors and so on. In this thesis, the manipulation of transition metal oxide thin film orientations, both out-of-plane and in-plane directions, on arbitrary substrates is studied by two methods: oxide nanosheets and single crystal substrates with a sacrificial layer. Regarding the first approach using oxide nanosheets, they can serve as templates for the thin film growth of transition metal oxides in one preferred out-of-plane orientation, enabling the free choice of substrates for both fundamental studies and practical applications. The reasons are that atomic-flat oxide nanosheets have a wide range of lattice constants and various 2D lattice symmetries, and they are easily deposited on any substrate surfaces through solution-based Langmuir-Blodgett technique. Concerning the second approach using single crystal substrates, the epitaxial lift-off of single crystalline oxide perovskite thin films with different orientations is realized using sacrificial layers deposited on single crystal substrates.