In Situ Adjustable Nanogaps and In-Plane Break Junctions

The ability to precisely regulate the size of a nanogap is essential for establishing high-yield molecular junctions, and it is crucial for the control of optical signals in extreme optics. Although remarkable strategies for the fabrication of nanogaps are proposed, wafer-compatible nanogaps with freely adjustable gap sizes are not yet available. Herein, two approaches for constructing in situ adjustable metal gaps are proposed which allow angstrom ngstrom modulation resolution by employing either a lateral expandable piezoelectric sheet or a stretchable membrane. These in situ adjustable nanogaps are further developed into in-plane molecular break junctions, in which the gaps can be repeatedly closed and opened thousands of times with self-assembled molecules. The conductance of the single 1,4-benzenediamine (BDA) and the BDA molecular dimer is successfully determined using the proposed strategy. The measured conductance agreeing well with the data by employing another well-established scanning tunneling microscopy break junction technique provides insight into the formation of molecule dimer via hydrogen bond at single molecule level. The wafer-compatible nanogaps and in-plane dynamical break-junctions provide a potential approach to fabricate highly compacted devices using a single molecule as a building block and supply a promising in-plane technique to address the dynamical properties of single molecules.

Automated summary

The ability to regulate nanogap size is essential for molecular junctions and control of optical signals. This study proposes two approaches for in situ adjustable metal gaps with high resolution, which can be used in wafer-compatible nanogaps and in-plane molecular break junctions. These adjustable nanogaps allow for repeated opening and closing, providing insights into the conductance of single molecules and molecular dimers. The wafer-compatible nanogaps and in-plane break-junctions offer potential for compact devices and dynamical studies of single molecules.