Interplay between Switching Driven by the Tunneling Current and Atomic Force of a Bistable Four-Atom Si Quantum Dot

We assemble bistable silicon quantum
dots consisting of four buckled atoms (Si4-QD) using atom
manipulation. We demonstrate two competing atom switching mechanisms,
downward switching induced by tunneling current of scanning tunneling
microscopy (STM) and opposite upward switching induced by atomic force
of atomic force microscopy (AFM). Simultaneous application of competing
current and force allows us to tune switching direction continuously.
Assembly of the few-atom Si-QDs and controlling their states using
versatile combined AFM/STM will contribute to further miniaturization
of nanodevices.