Single-Atom Switches and Single-Atom Gaps Using Stretched Metal Nanowires

Abstract

Utilizing individual atoms or molecules as functional units in electronic circuits meets the increasing technical demands for the miniaturization of traditional semiconductor devices. To be of technological interest, these functional devices should be high-yield, consume low amounts of energy, and operate at room temperature. In this study, we developed nanodevices called quantized conductance atomic switches (QCAS) that satisfy these requirements. The QCAS operates by applying a feedback-controlled voltage to a nanoconstriction within a stretched nanowire. We demonstrated that individual metal atoms could be removed from the nanoconstriction and that the removed metal atoms could be refilled into the nanoconstriction, thus yielding a reversible quantized conductance switch. We determined the key parameters for the QCAS between the "on" and "off" states at room temperature under a small operating voltage. By controlling the applied bias voltage, the atoms can be further completely removed from the constriction to break the nanowire, generating single-atom nanogaps. These atomic nanogaps are quite stable under a sweeping voltage and can be readjusted with subangstrom accuracy, thus fulfilling the requirement of both reliability and flexibility for the high-yield fabrication of molecular devices.

Effect of H2O Adsorption on Negative Differential Conductance Behavior of Single Junction

“…Due to the rapid development of single molecular technologies 11–14 , great progresses have been achieved for single-molecule-device fabrications in recent years 15–18 . At the meantime, different strategies are designed to control and improve the functional properties of single molecular device 19–22 .…”

“…Utilizing single molecule as functional device in electronic circuit is an ultimate goal of molecular electronics, which has motivated scientists to devote themselves to the investigations of molecular devices for tens of years 1 – 10 . Due to the rapid development of single molecular technologies 11 – 14 , great progresses have been achieved for single-molecule-device fabrications in recent years 15 – 18 . At the meantime, different strategies are designed to control and improve the functional properties of single molecular device 19 – 22 .…”

A flexible platform for controlled optical and electrical effects in tailored plasmonic break junctions

“…The current here amounts to 4 nA at a bias voltage of 50 mV. For even narrower gaps, several processes may take place that can lead to dynamic modifications, such as thermal mobility of the gold atoms and electromigration [31,32], or local modification of the junction, for example, by attraction of contaminants to high field regions. For lower currents, the MCBJs tend to drift apart.…”

Shaping the Atomic‐Scale Geometries of Electrodes to Control Optical and Electrical Performance of Molecular Devices

“…Two types of electrodes were fabricated: one is an atomic‐scale sharp electrode fabricated by mechanically one‐way stretching a gold nanowire (Figure b–e) and the other is an atomic‐scale planar electrode fabricated by several repeated stretch–recompress processes applied on a microwire. For the fabrication of atomic‐scale sharp electrodes, a suspended nanowire with a double‐cone‐shaped constriction was prefabricated on the substrate as we previously reported . Notably, to obtain a pair of electrodes with atomic‐scale sharp tips, (1) we employed electron beam lithography to create the nanoscale bridge, i.e., the diameter of constriction can be reduced to ≈ 30 nm, which facilitates the elongation of the metal bridge during the stretch process; (2) we prehardened the polyimide insulation layer under high vacuum to prevent any unexpected deformation and to suppress the drift of the nanogap size; and (3) we use a low stretching rate (0.1 nm s −1 ) to stretch the metal bridge; in this way, a pair of atomic‐scale sharp electrodes, even metal atom chain, can be automatically generated.…”