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Conductance Oscillations in Core/Shell Nanowires

In semiconductor nanowires consisting of a conductive InAs shell covering a nonconductive GaAs core very regular magneto-conductance oscillations were observed. The oscillation period exactly corresponds to a magnetic flux quantum.

In the past, often semiconductor nanowires were made of a single material, e.g. InAs. Based on these nanowires transistors can be realized, where the conductive channel consists of a high electron mobility material. A high electron mobility directly results in a higher switching speed. Recently, nanowire structures were fabricated, which consist of combinations of different materials. In Jülich we pursued the approach to cover a nonconductive GaAs core with a conductive InAs shell. By that a tube-like conductor is formed.

GaAs/InAs Core/Shell NanowireGaAs/InAs Core/Shell nanowire grown by molecular beam epitaxy
Source: Torsten Rieger, Dr. Mihail Ion Lepsa, PGI-9

By applying an increasing magnetic field along the nanowire axis very regular magneto-conductance oscillations are observed at low temperature. These oscillations originate from electron interference effects. Particularly at low temperatures the wave properties of electrons are visible. The superposition of these electrons waves lead to interference phenomena, i.e. an enhancement (constructive interference) or a cancelation (destructive interference). By applying a magnetic field the interference pattern measured by the conductance can be shifted periodically. Electron interference effects might be used for switching purpose in future nano-scaled devices. An advantage would be the superior energy efficiency compared to conventional devices.

Further information: Nanotechnology Article

Magnetoconductance Oscillations Magnetoconductance Oscillations: The conductance is plotted in units of the conductance quantum. The oscillation period corresponds to a magnetic flux quantum.
Source: Önder Gül, PGI-9


Prof. Dr. Thomas Schäpers