Semiconducting Nanowires – Tail Tale

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Haim Beidenkopf
29/10/2015 - 13:30 - 12:30
Resnick Building (209), room 210

Semiconducting nanowires have captured vast scientific attention ever since the first detection of a zero-bias conductance peak – possibly signifying a Majorana mode. It is therefore surprising how little information we gained in the time that have passed since that report. A major experimental obstacle is the brittleness and reactivity of the nanowires, that oxidize once brought into ambient conditions. By tackling this technological challenge we have been able to study spectroscopically the one-dimensional electronic states in bare InAs semiconducting nanowires. We visualize the one dimensional channels through the scattering of the electrons from point impurities on the surface of the nanowire. A series of stacking faults in the crystallographic structure form a Fabry-Perot interferometer that quantizes these states into resonances and allows us to extract the relaxation rate of these electrons as well as the strength of stacking fault as scatterers. Finally, at the end of the nanowire, where the Majorana modes should reside in the topological superconducting case, we find plethora of electronic states. These include quantized quantum-dot states at the tip of the nanowire that leak into the nanowire with strong electron-hole asymmetry, and a one-dimensional state that decays into the nanowire revealing an uncharted nonmonotonic regime in the decoherence of electrons in one dimension.