Preselectable integer quantum conductance of electrochemically fabricated silver point contacts

Abstract

The controlled fabrication of well-ordered atomic-scale metallic contacts is of great interest: it is expected that the experimentally observed high percentage of point contacts with a conductance at noninteger multiples of the conductance quantum G0=2e2∕h in simple metals is correlated to defects resulting from the fabrication process. Here we demonstrate a combined electrochemical deposition and annealing method that allows the controlled fabrication of point contacts with preselectable integer quantum conductance. The resulting conductance measurements on silver point contacts are compared with tight-binding-like conductance calculations of modeled idealized junction geometries between two silver crystals with a predefined number of contact atoms.

The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale

“…e results indicate that switching occurs by a reversibly rearrangement of the contacting group of atoms between two different stable configurations with a potential barrier between them. For silver the observed quantum conductance levels appear to coincide with integer multiples of the conductance quantum [1,10]. e observed integer conductance levels of the switch are determined by the available bistable junction conformations, similar to the observation of preferential atomic configurations in metallic clusters corresponding to "magic numbers" [12].…”

“…Figure 4 shows a sequence of reproducible switching events between an insulation "off-state" and a quantized conducting "on-state" (at 1 G 0 ), where the quantum conductance (red curves) of the switch is controlled by the gate potential (blue curves), as commonly observed in transistors. As calculations have shown [10], for atomic-scale silver contacts a quantized conducting "on-state" of 1 G 0 corresponds to a single-atom contact. When we set the gate potential to an intermediate "hold" level between the "on" and the "off" potentials, the currently existing state of the atomic switch remains stable, and no further switching takes place.…”

“…1) [1,6]. A comparison of the experimental data with theoretical calculations indicates perfect atomic order within the contact area without volume or surface defects [10]. …”

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ascinating physical properties and technological perspectives have motivated investigation of atomic-scale metallic point contacts in recent years [1][2][3][4][5][6][7][8][9][10]. e quantum nature of the electron is directly observable in a size range where the width of the contacts is comparable to the Fermi wavelength of the electrons, and conductance is quantized in multiples of 2e 2 /h for ballistic transport through ideal junctions [2].

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Resistive Switching in Bulk Silver Nanowire-Polystyrene Composites

“…[ 7 , 32-39 ] The local curvature of our silver nanowires is signifi cantly higher than that of fl at electrodes, so these geometrical considerations could make the electroformation of silver fi laments from our nanowires easier than fi lament formation from fl at electrodes. Additional support for the concept of silver fi lament formation can be found in reports by Xie, et al [ 44,45 ] In these studies, the authors report the solution-phase electroformation of silver fi laments between silver crystals on adjacent gold electrodes separated by a nanoscale gap. Their devices function as atomic switches, because their observed fi laments are suffi ciently small to observe quantized conductance values that vary with the fi lament diameter.…”