Journal
REVIEW OF SCIENTIFIC INSTRUMENTS
Volume 79, Issue 7, Pages -Publisher
AMER INST PHYSICS
DOI: 10.1063/1.2953097
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- Direct For Mathematical & Physical Scien
- Division Of Physics [830228] Funding Source: National Science Foundation
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We have constructed a scanning tunneling potentiometry system capable of simultaneously mapping the transport-related electrochemical potential of a biased sample along with its surface topography. Combining a novel sample biasing technique with a continuous current-nulling feedback scheme pushes the noise performance of the measurement to its fundamental limit-the Johnson noise of the scanning tunneling microscope (STM) tunnel junction. The resulting 130 nV voltage sensitivity allows us to spatially resolve local potentials at scales down to 2 nm, while maintaining angstrom scale STM imaging, all at scan sizes of up to 15 mu m. A millimeter-range two-dimensional coarse positioning stage and the ability to operate from liquid helium to room temperature with a fast turn-around time greatly expand the versatility of the instrument. By performing studies of several model systems, we discuss the implications of various types of surface morphology for potentiometric measurements. (C) 2008 American Institute of Physics.
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