Indium ad-dimer manipulation by an STM tip

When the forces between an STM tip and an adsorbate are comparable in magnitude to the forces between an adsorbate and a surface, the tip, instead of being a conventional imaging probe, can cause significant surface modifications. This technique is used in our study of In on Si(1 0 0) to manipulate the In ad-dimers on the surface. While voltage pulses alone yield a poor resolution in controlled positioning, the application of large currents accompanied by the close approach of the tip to the surface, appears promising in moving In ad-dimers from one location to another. Both the effects caused by the electric fields from voltage or current pulses and possible mechanisms on the surface modification will be briefly discussed.