Single-Crystal Au Triangles as Reconfigurable Contacts for Atomically Smooth Surfaces: Ultra-High Vacuum Transfer-Printing

In a planar atomic-scale device, defined nano-contacts to liaise between the atomic scale and the macroscale via the intermediate micron scale are crucial to ensure the atomic-scale circuit performances by minimizing the leakage current, minimizing cross talks, and minimizing contact resistance. Whether the macroscale contact is via a multi-probe system or via doped back interconnects preparing for a nano-packaging, defined and easily recognizable contact nano-pads are necessary. A new approach is presented here based on the in situ transfer of single Au crystals grown on a MoS2 surface in ultra-high vacuum (UHV) onto another surface where such metallic nano-crystal growth is usually not compatible. The molybdenite surface is particularly well suited to grow single Au nano-crystal triangles, and transfer-printing in ambient environment has already been successfully demonstrated. A dedicated transfer-printing tool was designed and constructed to perform this transfer printing task in a UHV environment. Preliminary results from scanning electron microscopy and low-temperature scanning tunneling microscopy are presented.