Quantum transport in scanning probe induced nanostructures
Dr. Nikola Pascher
IBM Research, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
17:00 - 18:00 Tuesday 23 June 2015 KFU HS 5.01 Semiconductor nanostructures are interesting playgrounds both for fundamental research in the field of experimental quantum physics as well as for forming quantum devices. We use two different approaches to control electron states with the help of scanning probe microscopes to locally induce and characterize semiconductor nanostructures.
First we show examples where the combination of lithographically defined topgates and the tip of the microscope as a scanning gate is used to form and tune a quantum point contact and a quantum dot in a high-mobility two-dimensional electron gas in a GaAs-AlGaAs heterostrucutre. Our setup consists of a scanning probe microscope in a mag¬netic field of up to 8 T and at a temperature of 100 mK. The measure¬ments give direct access to the real space behavior and distribution of integer and fractional quantum Hall edge channels close to the quantum device. Putting our results into a theoretical framework we can draw conclusions about the alternating compressible and incompressible stripes of electron liquid.
Secondly, on hydrogenated silicon (001) surfaces we can use a scanning tunneling microscope as a lithography tool by locally desorbing the hydrogen passivation with the tip. By exposing these patterns to gas-phase dopants, we can pattern atomically sharp dopant nanostructures in the silicon crystal.
• N. Pascher, C. Rössler, T. Ihn, K. Ensslin, C. Reichl, and W. Wegscheider, Phys. Rev. X 4, 011014 (2014): Imaging the conductance of integer and fractional quantum Hall edge states
• N. Pascher, F. Timpu, C. Rössler, T. Ihn, K. Ensslin, C. Reichl, and W. Wegscheider, Phys. Rev. B 89, 245408 (2014): Resonant electron tunneling in a tip-controlled potential landscape
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