title: Mechanically tunable sub-10 nm metal gap by stretching PDMS substrate.
abstract: Manipulating light in sub-10 nm or subnanometer metal nanogaps is crucial to study the strong interaction between electromagnetic waves and matters. However, the fabrication of metallic nanogaps with precisely controlled size and high-throughput still remains a challenge. Here, we developed an approach to actively control the gap distance between adjacent metal nanoparticles from 140 nm to sub-10 nm or even 0 nm via mechanical stretching process. To demonstrate this method, we manufactured the gold disk arrays in a square lattice on the polydimethylsiloxane (PDMS) substrate through interference lithography and gold deposition, and sub-10 nm interparticle gap was achieved as exerting a strain of 100% to the PDMS substrate. Transmission spectra show a remarkable red shift of the dipole resonance with narrowing gap from 140 nm to sub-10 nm. Importantly, a universal scaling law between the gap distance in nanoscale and the stretching amount of PDMS substrate in macroscopic scale were demonstrated experimentally and theoretically. Our method can tune the gap distance continuously and reversibly, suggesting potential applications in surface-enhanced Raman scattering, single photon emitter and quantum tunneling of electric charge.
authors.affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Liu
authors.forename: Yang
authors.initials: Y
authors.lastname: Shen
authors.forename: Guohui
authors.initials: G
authors.lastname: Xiao
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: She
authors.forename: Jianfang
authors.initials: J
authors.lastname: Wang
authors.forename: Chongjun
authors.initials: C
authors.lastname: Jin