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 degrees 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 omega/2 theta 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.