Nanometer-size surface modifications with preserved atomic order generated by voltage pulsing

We report on the generation of atomically resolved nanometer-size surface modifications by applying voltage pulses at predefined locations on the surface of the layered semiconductor tungsten diselenide (WSe2). Time-stable structures with diameters between 8 nm and less than 1 nm have been reproducibly written both in air and under vacuum. For small diameters, the resulting structures have the shape of mounds, whereas for diameters in excess of about 4 nm, a ring-like appearance is observed. In both cases, the atomic order of the formerly undisturbed surface is preserved and no defects in the lateral atomic order of the surface layer are found.