Abstract
We investigate the electron transport between a scanning tunneling microscope tip and Si(100)-2 x 1 surfaces with four distinct configurations by performing calculations using density functional theory and the nonequilibrium Green's function method. Interestingly, we find that the conducting mechanism is altered when the tip surface distance varies from large to small. At a distance larger than ...
Abstract
We investigate the electron transport between a scanning tunneling microscope tip and Si(100)-2 x 1 surfaces with four distinct configurations by performing calculations using density functional theory and the nonequilibrium Green's function method. Interestingly, we find that the conducting mechanism is altered when the tip surface distance varies from large to small. At a distance larger than the critical value of 4.06 angstrom, the conductance is increased with a reduction in distance owing to the pi state arising from the silicon dimers immediately under the tip; this in turn plays a key role in facilitating a large transmission probability. In contrast, when the tip is closer to the substrate, the conductance is substantially decreased because the pi state is suppressed by the interaction with the tip, and its contribution in the tunneling channels is considerably reduced.
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