In-situ control of on-chip angstrom gaps, atomic switches, and molecular junctions by light irradiation

Abstract Pairs of electrodes with nanometer gap, termed as nano-gapped electrodes, are fundamental building blocks for the fabrication of nanometer-sized devices and are essential for the examination of molecular properties and extreme nano-optics. Although modern fabrication techniques make it feasible to fabricate nanometer gaps, it is still a formidable challenge to fabricate adjustable gaps arrays with angstrom precision. Here, we demonstrate that in-situ adjustable nanogaps (arrays) with sub-angstrom precision can be fabricated via laser irradiation on the substrate which supports the electrode pairs. We further demonstrate that atomic-level metal contacts can be switched and the direction of the switching can be selectively controlled by the laser irradiation position. By varying the laser power gradually, the nanogap’s size can be continuously changed, providing a reliable break junction technique to address the properties of single-molecule junctions. The small spatial focus size of the laser beam makes it feasible to realize addressable on-chip molecular junction arrays.