A Direct Determination of the Structure of Polar SrTiO3 on Silicon

The epitaxial growth of perovskite oxide structures on silicon substrates has opened the door for the integration of a wide range of novel physical properties unique to complex oxides with established silicon-based technologies. A model system is the polar SrTiO3/Si system. Synchrotron based x-ray diffraction measurements allow a direct determination of the structure of the SrTiO3-Si interface, as well as the atomic displacements in the SrTiO3 film. A combination of direct phasing methods and fitting algorithms is used to convert the diffraction data into sub-angstrom resolution real space structural maps. The results can be used to understand the polarization observed in the SrTiO3 thin films and the measured differences between 2.5 and 5 unit cell SrTiO3 deposited on Si.