A generalized diffraction approach to predict the coupling of interface structure and function with lattice displacements*

Abrupt changes in symmetry, bonding and structure strongly affect functional behavior at oxide-semiconductor interfaces. In this talk, we consider specific examples of crystalline BaO and SrTiO$_{3}$ deposited on Si. Charge transfer at the interface between the oxide and semiconductor is found using synchrotron x-ray diffraction. This charge movement couples to optical modes in the BaO and SrTiO$_{3}$ layers. This effect extends deep into the films because the polarization of the optical mode is not effectively screened in the insulating BaO and SrTiO$_{3}$ layers. Differences in atomic displacements between the BaO and SrTiO$_{3}$ thin films result in a polarization that alternates sign in the case of BaO, as opposed to a uniform polarization in SrTiO$_{3}$. These differences impact on the electronic properties of the system, including how the semiconductor and oxide bands align.