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Ferroelectric Surface Properties
Scope and goals of research project:
We propose to explore the use of ferroelectric surface potentials and surface charges for an exciting and unique set of applications, including local molecular self-assembly, local physical adsorption/desorption, local chemical reactions, local charge transfer reactions, and the manipulation of individual organic molecules. We believe these unique surfaces can be utilized as writable and re-usable templates for nanoscience and technology.
On the surface of an ideal dielectric ferroelectric, the abrupt change in the normal component of the spontaneous polarization will result in the appearance of a surface bound polarization charge. This bound charge results in a significant electric field in and near the surface of the ferroelectric. The properties of the surface and the presence of charges within the ferroelectric material will affect this polarization field and significantly influence the surface field and the surface potential.
In this project we will employ UHV surface spectroscopies in concert with in situ surface processing to establish the effectiveness of our approach. We will use UV photo-emission spectroscopy (UPS) to establish the surface Fermi level and the electron affinity of the surface. This technique will also be employed to establish the presence and energy of surface states. We will then employ in situ x-ray photoemission spectroscopy (XPS) to verify the surface band bending and the surface chemistry of the surface.
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| Figure 1: |
A photo electron emission microscopy image demonstrating polarization-dependent emission.
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| Figure 2: |
Schematics of the charges at the ferroelectric surface of neg. and pos. domains. Note the change in electron affinity.
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