One-Stage Hydrothermal Growth and Characterization of Epitaxial LaMnO₃ Films on SrTiO₃ Substrate

Epitaxial LaMnO₃ thin films were grown on SrTiO₃ substrate using a one-stage hydrothermal route from La(NO₃)₃, MnCl₂ and KMnO₄ in an aqueous solution of 10 M KOH at 340 °C. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) indicate full coverage of LaMnO₃ on the substrate. X-ray diffraction in the symmetric ω/2θ mode suggests the film has an out-of-plane preferred orientation along the [001] direction of the substrate. The LaMnO₃ epitaxial thin film growth mechanism is proposed based on the analysis of the atomic sharp interface formed between LaMnO₃ and the SrTiO₃ substrate, as seen by aberration-corrected scanning transmission electron microscopy (AC-STEM) imaging in combination with electronic energy loss spectroscopy (EELS). Compared with the conventional vapor deposition methods, the one-stage hydrothermal route opens up a new way to fabricate complex oxide epitaxial heterostructures.