Dual scanning tunneling microscope mode of the surface diffusion metal ion source: Li transfer and scanning

Application of the new solid-state lithium surface diffusion metal ion source in the scanning tunneling microscope (STM) mode under ultrahigh Vacuum conditions is reported. By applying positive voltage pulses to a Li-covered tungsten STM tip placed within tunneling range, single nanosized Li hillocks and stripe-shaped Li formations are created on the Pt(110) surface in a well-reproducible way. The transfer of Li to the sample surface occurs in a noncontact way via chemically assisted field desorption of Li from the apex of the tip. The supply of Li to the apex surface sites is provided by surface diffusion from a Li monolayer deposit on the shank of the tip. The topography and evolution of the fabricated Li nanoformations are probed in situ using the same tip in the conventional STM imaging mode. (C) 1997 American Vacuum Society.