A scanning tunneling microscope with low-frequency modulation in the Z piezo is used to study conductance quantization of Au point contacts at ambient pressure and room temperature. Conductance up to 40 multiples of (Formula presented) can be repeatedly generated by pressing and pulling a Au tip against a Au sample with a sinusoidal distance modulation. By applying a symmetric double-cone model, only one parameter, the cone angle, is needed to describe the overall geometry of the contact. A conductance histogram in the low-conductance range is then tabulated as a function of the cone angle. The value of the conductance is found to decrease from the idealized value, (Formula presented) by an amount which increases with the angle of the cone. The distribution of the first conductance peak is analyzed to study the effect of the modulation speed. The peak width broadens as the speed is increased from 400 to 1000 Å/s.
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 15 Jan 1999|