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Nanoscale Charge Transport Studied by Multi-Tip Scanning Probe Microscopy

Welcome to the research group of Bert Voigtländer

We use multi-tip SPM like a multimeter on the nanoscale in order to study nanoscale charge transport properties at surfaces and nanostructures. On the one hand we develop novel multi-tip SPM instruments and measurement techniques, on the other hand we apply this new technique in order to reveal nanoscale charge transport properties, like

  • current flow around nanoscale defects (potentiometry),
  • resistance profiling along freestanding nanowires,
  • disentangling surface from bulk conductivity.

We investigate the intriguing charge transport properties of topological insulators, novel 2D materials, and nanowires.


Focus

potentiometry

Charge Transport through Surfaces

The increasing importance of surface conductance compared to conductance through the (semiconductor) bulk in modern nanoelectronic devices calls for a reliable determination of the surface conductivity We use distance dependent four-probe measurements in order to disentangle surface from bulk conductivity. Alternatively tunneling potentiometry (STP) allows to map the potential landscape while a current flows through the surface / nanostructure under study. Potentiometry maps give insight into fundamental transport properties, such as the influence of defects on the local electric transport. More: Charge Transport through Surfaces …

nanowires

Charge Transport through Nanostructures

We perform nanoscale resistance mapping along freestanding (“as grown”) GaAs nanowires with a diameter of ~100 nm. From the resistance profile information about the dopant incorporation in the nanowires is obtained. In the STM based approach of nano-contacting, four-point measurements can be performed not only in one signle configuration, as it is the case for the ligthographic approach, but many configurations can be measured by moving the tips along the nanowire. More: Charge Transport through Nanostructures …

4 tip stm 2

Multi-tip SPM Instrument Development

Since microelectronics evolves into nanoelectronics, it is essential to perform electronic transport measurements at the nanoscale. Our approach for the contacting of nanostructures is to use the tips of a multi-tip scanning probe microscope, in analogy to the test leads of a multimeter used at the macroscale. We designed an ultra-compact multi-tip STM with is our “multimeter at the nanoscale”. More: Multi-tip SPM Instrument Development …



Microscope films microscope

STM movies

Image gallery

Finished projects

KoalaDrive

Book on SPM

People

  • Prof. Dr. Bert Voigtländer
  • Dr. Vasily Cherepanov
  • Dipl.-Ing. Peter Coenen
  • Helmut Stollwerk
  • Dr. Richard Spiegelberg
  • Dr. Stefan Korte
  • Dr. Martin Grob
  • M. Sc. Felix Lüpke
  • M. Sc. Sven Just
  • M. Sc. David Cuma
  • M. Sc. Arthur Leis

Conctact:

Prof. Dr. Bert Voigtländer
Forschungszentrum Jülich PGI-3
52425 Jülich Germany
Tel. + 49 2461 61 4116
Fax + 49 2461 61 8216
e-mail: b.voigtlaender@fz-juelich.de


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