AVS 50th International Symposium
    Nanometer Structures Tuesday Sessions
       Session NS-TuP

Paper NS-TuP14
In-situ Tip Preparation and Nanoscale Surface Modification using STM Manipulation

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: V. Iancu, Ohio University
Authors: V. Iancu, Ohio University
A. Deshpande, Ohio University
S.-W. Hla, Ohio University
Correspondent: Click to Email
Single atom manipulation@foontote 1,2@ with a scanning tunneling microscope (STM) tip on crystal surfaces requires an extremely fine control over the tip-atom-surface junction. The shape of the STM-tip and the chemical elements that constitute the tip-apex are vital for a successful atom manipulation with atomic scale precisions. Here we report an in-situ tip preparation technique useful to fabricate stable STM-tips with a known chemical element at the tip-apex. The experiments are conducted at an ultra-high-vacuum conditions on a Ag(111) surface at 4.8 and 75 K sample temperatures. During the experiment, the STM-tip, made of polycrystalline tungsten wire, is gently dipped into the substrate and the tunneling voltage is increased to 3 V. The penetration depth is precisely controlled. The shape of the holes created by the tip dipping indicates that the tip becomes sharper by repeating the procedure. This is due to the local heating during the tip-sample mechanical contact that re-shapes the structure of the tip-apex. In addition, variation of the tip-height and tunneling voltage during the procedure results in different impact force. By applying suitable impact force with the STM-tip, atomic scale surface steps and Ag islands can be created locally. This entire procedure will be useful to conduct new nanoscale experiments or to test the strength of the material at an atomic level. @FootnoteText@@footnote 1@S.-W. Hla, K.-F. Braun, K.-H. Rieder, "single atom manipulation mechanisms during a quantum corral construction",Phys. Rev. B rapid communication (2003) in press.@footnote 2@S.-W. Hla, L. Bartels, G. Meyer, K.-H. Rieder,"Inducing all steps of a chemical reaction with the scanning tunneling microscop tip: Towards single molecule engineering", Phys. Rev. Lett. 85 (2000) 2777-2780.