Epitaxial growth of the first two members of the Ban+1InnO2.5n+1 Ruddlesden–Popper homologous series

We demonstrate the epitaxial growth of the first two members, and the n=∞ member of the homologous Ruddlesden–Popper series of Ban+1InnO2.5n+1 of which the n=1 member was previously unknown. The films were grown by suboxide molecular-beam epitaxy where the indium is provided by a molecular beam of indium-suboxide [In2O (g)]. To facilitate ex situ characterization of the highly hygroscopic barium indate films, a capping layer of amorphous SiO2 was deposited prior to air exposure. The structural quality of the films was assessed by x-ray diffraction, reflective high-energy electron diffraction, and scanning transmission electron microscopy.