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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.

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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”.

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Ultra-small nanocrystals

Nanoparticles and quantum dots are of great interest due to their optical, electronic and structural properties which are dominated by quantization effects. For ultra-small particles (< 5 nm) a precise structural characterization is very difficult. We utilize x-ray diffraction at synchrotron sources combined with a novel data analysis method for powder-diffraction data to investigate size, shape, structure (including impurities and stacking faults) stress, relaxation effects, etc. Also ensemble properties like size distributions can be analysed.Appl. Phys. A 85 (4), 337 (2006)

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