Observing the microstructure of a (001) κ-Ga2O3 thin film grown on a (−201) β-Ga2O3 substrate using automated crystal orientation mapping transmission electron microscopy

Abstract

We grew (001) κ-Ga₂O₃ thin films on (−201) β-Ga₂O₃ substrates using mist chemical vapor deposition. X-ray diffraction analysis revealed that the thin films grown at 450–800 °C showed (004) κ-Ga₂O₃ and (−402) β-Ga₂O₃ diffraction peaks. Scanning electron microscopy observations showed that the thin films grown at 750 and 850 °C had stripe morphologies owing to the presence of (−201) β-Ga₂O₃ and triangular and hexagonal morphologies attributed to (001) κ-Ga₂O₃, indicating the presence of β-Ga₂O₃ in the κ-Ga₂O₃ thin films. Although no striped structure was observed on the surface of the film grown at 650 °C, scanning transmission electron microscopy (STEM) observations showed that β-Ga₂O₃ existed at the substrate interface. Furthermore, automated crystal orientation mapping STEM revealed that β-Ga₂O₃ existed near the surface as well as the substrate interface of the thin films.