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Nanoscale Charge Transport of Quantum Materials 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 of quantum materials 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 quantum materials like topological insulators, novel 2D materials, and nanowires.



Charge Transport through Surfaces

Scanning 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 of quantum materials, such as the influence of defects on the local electric transport. 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.


Charge Transport through Nanostructures of Quantum Materials

Multi-tip STM is used to reveal detailed transport properties of thin films of the promising topological insulator (TI) material BiSbTe3. To shed light on parallel transport channels in these quantum materials we use gated four-tip scanning tunneling microscopy to obtain conductivities, charge carrier concentrations, and mobilities. 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.

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”.

Microscope Films Microscope

STM Movies

Image Gallery

Finished Projects


Book on SPM

Book on AFM


  • Prof. Dr. Bert Voigtländer
  • Dr. Vasily Cherepanov
  • Dr. Timofey Balashov
  • (Dipl.-Ing. Peter Coenen)
  • (Helmut Stollwerk)
  • M. Sc. David Cuma
  • M. Sc. Arthur Leis

Recent Alumni

  • Dr. Richard Spiegelberg (FH Furtwangen)
  • Dr. Felix Lüpke (Oak Ridge National Laboratory (ORNL))
  • M. Sc. Sven Just (RWTH Aachen)


Prof. Dr. Bert Voigtländer
Forschungszentrum Jülich PGI-3
52425 Jülich Germany
Tel. + 49 2461 61 4116
Fax + 49 2461 61 8216