  Molecules with versatile functionalities and well-defined structures, can
serve as building blocks for extreme nanoscale devices. This requires their
precise integration into functional heterojunctions, most commonly in the form
of metal-molecule-metal architectures. Structural damage and nonuniformities
caused by current fabrication techniques, however, limit their effective
incorporation. Here, we present a hybrid fabrication approach enabling uniform
molecular gaps. Template-stripped lithographically-patterned gold electrodes
with sub-nanometer roughness are used as the bottom contacts upon which the
molecular layer is formed through self-assembly. The top contacts are assembled
using dielectrophoretic trapping of colloidal gold nanorods, resulting in
uniform sub-5 nm junctions. In these electrically-active designs, we further
explore the possibility of mechanical tunability. The presence of molecules may
help control sub-nanometer mechanical modulation which is conventionally
difficult to achieve due to instabilities caused by surface adhesive forces.
Our approach is versatile, providing a platform to develop and study active
molecular gaps towards functional nanodevices.
