AVS 60th International Symposium and Exhibition
    Scanning Probe Microscopy Focus Topic Thursday Sessions
       Session SP+AS+BI+MI+NS+SS-ThM

Paper SP+AS+BI+MI+NS+SS-ThM3
Tunneling Resonances Into Engineered Nanoscale Cavities on a Noble Metal Surface

Thursday, October 31, 2013, 8:40 am, Room 202 C

Session: Advances in Scanning Probe Imaging
Presenter: A. DiLullo, Ohio University
Authors: A. DiLullo, Ohio University
D. Acharya, Ohio University
N. Takeuchi, Universidad Nacional Autónoma de México
S.-W. Hla, Ohio University
Correspondent: Click to Email
Variations in surface topologies such as step edges and surface defects are known to alter the electrochemical properties of the surfaces. The ability to directly alter surface topologies on the nanoscale in order to achieve desired properties is useful. We report on the direct modification of local surface topologies and the resulting changes in local electronic properties. Surface vacancies on a Ag(111) surface are created by probe manipulations using a scanning tunneling microscope operated at 78 K. Tunneling resonances, found at certain probe-sample biases, are determined by analysis of spatial height-differential mapping (dz/dV). The resonances, when considered over paths crossing the induced surface vacancies, significantly shift when comparing clean terraces to vacancy positions. These resonances originate as a result of field emission where the emitted electron has greater energy than the surface potential (work function) at the probe lateral position. By fitting these resonances to the Gundlach equation describing resonant tunneling it is possible to extract the tip work function, sample work function at probe position, and absolute tip height from the sample. The shift in resonances at vacancy locations is related to the variation in the work function due to local topology. It is important to be able to tune the work function as it plays a large role in many surface processes and properties. The created surface vacancies may then be considered local wells having work functions differing from the supporting substrate, with resonances tunable by probe manipulations, and may be useful for nanotechnological applications.