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arXiv · 0804.2735

Design and Performance of a Practical Variable-Temperature Scanning Tunneling Potentiometry System

M. Rozler·M. R. Beasley
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Abstract

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 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 um. A mm-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.

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M. Rozler, M. R. Beasley. 2008-06-04. Design and Performance of a Practical Variable-Temperature Scanning Tunneling Potentiometry System. https://doi.org/10.1063/1.2953097

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