Structure and Tensile Force of Nanometer- and Atomic-Sized Gold Contacts during Conductance Feedback Control

概要

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Nanometer- and atomic-sized gold (Au) contacts were produced by the retraction of a Au nanotip from contact with a Au plate at room temperature inside a transmission electron microscope. The nanotip–plate distance was controlled using a conductance feedback system. Au contacts showing certain conductance were observed continuously by in situ lattice imaging with simultaneous force measurements. When feedback conductance was selected to be $1G_{0}$ (where $G_{0} = 2e^{2}/h$, where $e$ is the charge of an electron and $h$ Planck’s constant), three types of Au contacts, i.e., zero-length contacts of one-, two-, and three-atom width, were observed under a stress of ${\sim}8$ GPa with a counting ratio of 54, 36, and 10%, respectively. Similarly, for feedback conductance of $2G_{0}$, $3G_{0}$, $4G_{0}$, and $5G_{0}$, Au contacts of one- to five-atom width were observed. Thus, it was demonstrated that a certain conductance corresponding to a quantized level is caused by several types of contacts.
2009-12-25