Photoemission study of Zr- and Hf-silicates for use as high-κ oxides: Role of second nearest neighbors and interface charge

We show a systematic trend of x-ray photoelectron binding energy shifts for Zr- and Hf-silicates, which are related to the composition of the films. The binding energy for the core photoelectrons can shift by up to 2 eV, depending on the relative electronegativities of the second nearest-neighbor elements. Understanding these shifts helps determine the underlying local electronic and chemical nature of the silicate network. Furthermore, we explain how charge at the dielectric-semiconductor interface can lead to shifts in the measured Si 2p peak binding energy by as much as 1 eV. The direction and magnitude of the binding energy shift can be used to determine the sign and density of the charge at the interface.