Nanostructure fabrication using laser field enhancement in the near field of a scanning tunneling microscope tip

The scanning tunneling microscope (STM) has been combined with laser excitation and was used for modification of metal surfaces in air. This technique enables processing of structures with a lateral resolution of approximately 10 nm. The form of the created features ranges from craters and ditches to hillocks. The process has been demonstrated on gold and gold/palladium substrates by utilization of tungsten, silver, and platin/iridium tips. Using pure silver tips or silver-coated tungsten tips, a transfer of tip atoms to the substrate occurred. In the case of uncoated tungsten tips, we observed substrate evaporation and surface grain reorganization at low laser intensities, respectively. No distortion of the employed tips during the structuring process was observed. Several future oriented applications are conceivable, such as, for example, high density data storage and fresnel optics for x rays. (C) 1996 American Institute of Physics.