Single-Domain and Atomically Flat Surface of κ-Ga2O3Thin Films on FZ-Grown ϵ-GaFeO3Substrates via Step-Flow Growth Mode

Abstract

Herein, single-domain κ-Ga2O3 thin films were grown on FZ-grown ϵ-GaFeO3 substrates via a step-flow growth mode. The ϵ-GaFeO3 possessing the same crystal structure and similar lattice parameters as those of the orthorhombic κ-Ga2O3 facilitated the growth of κ-Ga2O3 thin films, as observed by the X-ray diffraction (XRD) analysis. Furthermore, the surface morphologies of the κ-Ga2O3 thin films exhibited a step-terrace and atomically flat structure. XRD φ-scan and transmission electron microscopy with selected area electron diffraction revealed that there is no occurrence of in-plane rotational domains in the κ-Ga2O3 thin films on ϵ-GaFeO3 substrates and that the κ-Ga2O3 thin film comprised a single domain. TEM analysis revealed that there were no clear dislocations in the observation area. Moreover, high-resolution TEM observation showed that the atomic arrangements of the film and the substrate were continuous without the presence of an intermediate layer along the growth direction and were well-aligned in the in-plane direction.