Self-Aligned Formation of Sub 1 nm Gaps Utilizing Electromigration during Metal Deposition

Abstract

We developed a procedure for the fabrication of sub 1 nm gap Au electrodes via electromigration. Self-aligned nanogap formation was achieved by applying a bias voltage, which causes electromigration during metal evaporation. We also demonstrated the application of this method for the formation of nanogaps as small as 1 nm in width, and we found that the gap size can be controlled by changing the magnitude of the applied voltage. On the basis of the electric conductance and surface-enhanced Raman scattering (SERS) measurements, the fabricated gap size was estimated to be nearly equal to the molecular length of 1,4-benzenedithiol (BDT). Compared with existing electromigration methods, the new method provides two advantages: the process currents are clearly suppressed and parallel or large area production is possible. This simple method for the fabrication of a sub 1 nm gap electrode is useful for single-molecule-sized electronics and opens the door to future research on integrated sub 1 nm sized nanogap devices.

Sub‐5 nm Metal Nanogaps: Physical Properties, Fabrication Methods, and Device Applications

“…Therefore, a feedback‐controlled electromigration technique was recently developed that actively adjusts the applied voltage in response to the changing conductance of the weak link to controllably create nanoscale junctions . Following the electromigration process, different types of nanogaps have been successfully fabricated . Henderson et al introduced sandwich‐type electrodes on the basis of depositing a gold layer directly on an oxidized aluminum gate, similar to three‐terminal devices .…”

“…Henderson et al introduced sandwich‐type electrodes on the basis of depositing a gold layer directly on an oxidized aluminum gate, similar to three‐terminal devices . Thus, the gap size can be simply controlled by changing the magnitude of the applied voltage, and the gap width of electromigration break nanogaps can be controlled to as small as 1 nm . In 2009, Prins et al made nanogaps with few‐atom contacts using feedback‐controlled electromigration …”

Single-molecule electronics: from chemical design to functional devices

“…[68][69][70] As described in the MCBJ section, Raman spectra and inelastic electron tunneling spectroscopy can supply a large amount of information about the configuration of the molecule in the EBJ produced gaps. [71][72][73][74] 2.4. Self-assembly of nanostructures…”

Facile Preparation of Ultrasmall Void Metallic Nanogap from Self‐Assembled Gold–Silica Core–Shell Nanoparticles Monolayer via Kinetic Control

“…For example, lithographically patterned metal electrodes can be either mechanically broken down to generate two metal electrodes with small gap or electrically broken through electromigration of gold atoms. [9][10][11][12] Some of metallic nanogaps with sub-10 nm gap size are fabricated by the combination of metal layer deposition to patterned template and the lift off process for removing the template. [13][14][15] Deposition of a sacrifi cial alumina layer between two metal layers on templates and the selective removal of the sacrifi cial layer by ion milling and chemical etching can also provide similar nanogap structures.…”