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Start of funding 01.07.2014
Electron optics and negative index of refraction in HgTe quantum wells
Prof. Dr. Hartmut Buhmann
University of Würzburg
Physikalisches Institut, EP3
Prof. Dr. David Goldhaber-Gordon
Stanford University
Department of Physics
The goal of this Würzburg-Stanford collaboration is to realize and characterize complex p-n
junctions on HgTe devices. HgTe is a topological insulator material with gapless spin-momentum
locked Dirac-like surface states. Depending on the Fermi energy the transport is either electron
(n)- or hole (p)-like. Thus creating locally n- or p-conducting areas will affect the propagation of
ballistic carriers. Like the diffraction in optics electron can now be guided depending on the
sequence of n- and p-conducting areas and the angle of injection. For this purpose HgTe devices
are grown on conducting GaAs substrates which can be used as a gate for a global control of the
carrier concentration and hence its polarity. Additional top gates can be implemented to form
various p-n-junctions in different geometry on a nanometer scale.