Single atom manipulation on silicon.

The mechanism of a single atom switch on silicon has been elucidated by a combination of detailed experiments and first principles theory. The objective of this research is to find ways to make simple atom-scale devices that work at room temperature and on silicon. The experiments were carried out on hydrogen- passivated silicon in ultra-high vacuum using a scanning tunneling microscope. By suitable choice of the voltage and
current between the metal tip of the STM and the surface, it is possible to move a single hydrogen atom back and forth between two neigbouring silicon dangling bonds in a controlled fashion. The mechanism is a current-induced excitation of a surface resonance which lowers the barrier for diffusion between the two sites.