Generation and manipulation of atomic-scale structures with the STM

The on-purpose modification of a solid (WSe2) on an atomic scale and without locally destroying the atomic order of the lattice is demonstrated with the STM using different writing techniques. While mechanical indentation leads to surface deformations which reflect the shape of the tunneling tip, the application of voltage pulses results in highly symmetric modifications with diameters between 8 nm and less than 1 nm. For the case of small pulse amplitudes (≈ 2 V), well-defined and oriented structures are produced which comprise only three atomic sites. The experiments are carried out under ambient conditions as well as in UHV, leading to comparable results. After their generation, nanometer-scale structures can be further manipulated in a controlled manner with the STM tip.