  Heteroepitaxial growth of transition-metal oxide films on the open (111)
surface of SrTiO3 results in significant restructuring due to the polar
mismatch. Monitoring the structural and composition on an atomic scale of
LaNiO3/SrTiO3 (111) interface as a function of processing conditions has
enabled the avoidance of the expected polar catastrophe. Using atomically
resolved transmission electron microscopy and spectroscopy as well as Low
energy electron diffraction, the structure of the thin film, from interface to
the surface, has been studied. In this paper, we show that the proper
processing can lead to a structure that is ordered, coherent with the substrate
without intermediate structural phase. Angle-resolved X-ray photoemission
spectroscopy shows that the oxygen content of thin films increases with the
film thickness, indicating that the polar mismatch is avoided by the presence
of oxygen vacancies.
