15 research outputs found
Gating a single-molecule transistor with individual atoms
Transistors, regardless of their size, rely on electrical gates to control the
conductance between source and drain contacts. In atomic-scale transistors,
this conductance is sensitive to single electrons hopping via individual
orbitals1, 2. Single-electron transport in molecular transistors has been
previously studied using top-down approaches to gating, such as lithography
and break junctions1, 3, 4, 5, 6, 7, 8, 9, 10, 11. But atomically precise
control of the gateâwhich is crucial to transistor action at the smallest size
scalesâis not possible with these approaches. Here, we used individual charged
atoms, manipulated by a scanning tunnelling microscope12, to create the
electrical gates for a single-molecule transistor. This degree of control
allowed us to tune the molecule into the regime of sequential single-electron
tunnelling, albeit with a conductance gap more than one order of magnitude
larger than observed previously8, 11, 13, 14. This unexpected behaviour arises
from the existence of two different orientational conformations of the
molecule, depending on its charge state. Our results show that strong coupling
between these charge and conformational degrees of freedom leads to new
behaviour beyond the established picture of single-electron transport in
atomic-scale transistors