Heteroepitaxial Hexagonal (00.1) CuFeO₂ Thin Film Grown on Cubic (001) SrTiO₃ Substrate Through Translational and Rotational Domain Matching

Abstract

Heteroepitaxy of complex oxide thin films is a significant challenge when a large mismatch in the lattice parameters (>8%) and difference in the crystallographic symmetry coexist between the film and substrate. Herein, the heteroepitaxial growth of a hexagonal delafossite CuFeO2 thin film with (00.1) orientation on a cubic perovskite (001) SrTiO3 substrate through translational and rotational domain matching epitaxy is reported. The rotational in‐plane domain orientation relationships are CuFeO2 [11.0]//SrTiO3 [110] and CuFeO2 [2.0]//SrTiO3 [110] with about 10% in‐plane lattice mismatch. The 14.8 nm‐thick (00.1) CuFeO2 thin film shows high‐crystalline quality with a full width at half maximum of rocking curve of about 0.24° and exhibits a possible indirect optical bandgap of 1.43 eV or direct optical bandgap of 1.94 eV. Herein, not only a model system demonstrating translational and rotational domain matching heteroepitaxy of complex oxides is reported, but also a way to thin‐film heterostructures integrating hexagonal delafossite with cubic perovskite materials for functional oxide devices is opened.

Formation of Quaternary Zn(Alxga1-X)2o4 Epilayers Driven by Thermally Induced Interdiffusion between Spinel Znga2o4 Epilayer and Al2o3 Substrate

“…The lattice distortion marked with an arrow at the interface between ZGO and sapphire is due to their lattice mismatch. The epitaxial {111} ZGO thin films grown on {001} sapphire substrates using MOCVD have been studied earlier [1,28,29]. It was observed that the apparent strain is released as the thickness increases and is caused due to misfit dislocations.…”