Abstract
Electronic switches with nanoscale dimensions satisfy an urgent demand for further device miniaturization. A recent heavily investigated approach for nanoswitches is the use of molecular junctions that employ photochromic molecules that toggle between two distinct isoforms. In contrast to the reports on this approach, we demonstrate that the conductance switch behavior can be realized with only a bare metallic contact without any molecules under light illumination. We demonstrate that the conductance of bare metallic quantum contacts can be reversibly switched over eight orders of magnitude, which substantially exceeds the performance of molecular switches. After the switch process, the gap size between two electrodes can be precisely adjusted with subangstrom accuracy by controlling the light intensity or polarization. Supported by simulations, we reveal a more general and straightforward mechanism for nanoswitching behavior, i.e., atomic switches can be realized by the expansion of nanoelectrodes due to plasmonic heating.
Highlights
Metallic quantum point contacts exhibit striking features, e.g., their atomic-scale dimension and electronic quantum transport, which have motivated extensive experimental and theoretical research in recent years[1,2,3,4,5]
Atomic switching of metallic quantum contacts In our experiments, a commercial light-emitting diode (LED) lamp is employed as the light source with an AC adapter to continuously control the intensity of light
We note that a prerequisite nanogap is needed to perform the gap size modulation by plasmonic heating in our experiments, this prerequisite nanogap can be generated by other fabrication techniques, such as electromigration, chemical deposition, shade evaporation, and a dash-in-line lithography technique[6]. With these on-chip fabrication techniques, a highly integrated nanogap array may be fabricated, which enables the realization of adjustable on-chip nanogaps controlled by light, which is unavailable for the mechanically controllable break junction (MCBJ) technique that is solely driven by piezo ceramics
Summary
Atomic switching of metallic quantum contacts In our experiments, a commercial light-emitting diode (LED) lamp is employed as the light source with an AC adapter to continuously control the intensity of light (see Supplementary Figure S1). This value is the well-known conductance quantum, which occurs when the size of a metallic contact is decreased to a single atom or a chain of gold atoms[28]. Our calculation shows that the gap size changes by only a few angstroms as the tunneling current changes from 10−5 G0 to 10−1 G0 (Supplementary Figure S4), which demonstrates that the distance between the two separated electrodes can be precisely controlled at subangstrom accuracy by the light intensity. To further clarify the mechanism for the lightcontrolled tunneling current, we investigate the current
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