Electronic Structure and Fermi Level Pinning Obtained with Spatially Resolved Electron Energy Loss Scattering
The electron microscope has made great strides towards obtaining direct structural images of buried defects and interfaces in metals and semi-conductors. In principle, electronic structure may also be obtained directly from the same areas by observing the electron energy loss scattering. Currently at IBM, the high resolution electron spectrometer on the HB501 scanning transmission electron microscope (STEM) is producing core loss spectra which show directly changes in electronic structure at defects and interfaces. This report describes briefly the basis for the technique, and an application to the Al/Si(111) interface. At this interface, new electronic states appear within the Si gap and the Si conduction bandstructure a few eV above the conduction band minimum is modified. These modifications are intimately related to the establishment of the Schottky Barrier, allowing a direct measurement of the local pinning of the Fermi level.
KeywordsScanning Transmission Electron Microscope Conduction Band Minimum Spin Orbit Splitting Atom Column Incident Beam Direction
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