Mechanically tunable sub-10 nm metal gap by stretching PDMS substrate

Area of Science:

• Nanotechnology
• Plasmonics
• Materials Science

Background:

• Precise control of sub-10 nm metal nanogaps is essential for studying light-matter interactions.
• Fabricating such nanogaps with high precision and throughput remains a significant challenge.

Purpose of the Study:

• To develop a novel method for actively controlling and tuning the gap distance between adjacent metal nanoparticles.
• To demonstrate the fabrication of sub-10 nm interparticle gaps using a mechanical stretching process.

Main Methods:

• Fabrication of gold disk arrays on a polydimethylsiloxane (PDMS) substrate via interference lithography and gold deposition.
• Mechanical stretching of the PDMS substrate to achieve tunable interparticle gaps, from 140 nm down to sub-10 nm.
• Analysis of transmission spectra to observe resonance shifts with varying gap distances.

Main Results:

• Achieved continuous and reversible tuning of metal nanogap distances from 140 nm to sub-10 nm by applying up to 100% strain to the PDMS substrate.
• Observed a significant red shift in the dipole resonance as the nanogap width decreased.
• Established a universal scaling law correlating nanoscale gap distance with macroscopic substrate stretching, validated both experimentally and theoretically.

Conclusions:

• The developed mechanical stretching method offers a viable approach for fabricating precisely controlled metal nanogaps.
• This technique holds promise for applications in surface-enhanced Raman scattering (SERS), single photon emitters, and quantum charge tunneling.
• The ability to tune nanogap distances continuously and reversibly opens new avenues for plasmonic and quantum devices.