Initiating and monitoring the evolution of single electrons within atom-defined structures

TL;DR

This paper demonstrates precise control and monitoring of single-electron charge states within atomically engineered silicon structures using non-contact atomic force microscopy, enabling site-specific manipulation without applied bias.

Contribution

It introduces a bias-free, mechanically based method for single-electron control in atom-defined structures, advancing atomic-scale charge manipulation techniques.

Findings

Achieved stable charge configurations at 4.5 K for seconds

Demonstrated control over charge states of up to six-atom structures

Identified short-range forces responsible for charge switching

Abstract

Using a non-contact atomic force microscope we track and manipulate the position of single electrons confined to atomic structures engineered from silicon dangling bonds (DBs) on the hydrogen terminated silicon surface. By varying the probe-sample separation we mechanically manipulate the equilibrium position of individual surface silicon atoms and use this to directly switch the charge state of individual DBs. Because this mechanism is based on short range interactions and can be performed without applied bias voltage, we maintain both site-specific selectivity and single-electron control. We extract the short range forces involved with this mechanism by subtracting the long range forces acquired on a dimer vacancy site. As a result of relaxation of the silicon lattice to accommodate negatively charged DBs we observe charge configurations of DB structures that remain stable for many seconds at 4.5 K. Subsequently we use charge manipulation to directly prepare the ground state and metastable charge configurations of DB structures composed of up to six atoms.