Electronic Phase Coherence in InAs Nanowires

Abstract

Magnetotransport measurements at low temperatures have been performed on InAs nanowires grown by In-assisted molecular beam epitaxy. Information on the electron phase coherence is obtained from universal conductance fluctuations measured in a perpendicular magnetic field. By analysis of the universal conductance fluctuations pattern of a series of nanowires of different length, the phase-coherence length could be determined quantitatively. Furthermore, indications of a pronounced flux cancelation effect were found, which is attributed to the topology of the nanowire. Additionally, we present measurements in a parallel configuration between wire and magnetic field. In contrast to previous results on InN and InAs nanowires, we do not find periodic oscillations of the magnetoconductance in this configuration. An explanation of this behavior is suggested in terms of the high density of stacking faults present in our InAs wires.

Monitoring structural influences on quantum transport in InAs nanowires

“…The theories used in this Letter have been developed for wires made from two-dimensional planar electron gases, i.a., they do not account for flux cancellation effects owing to the cylindrical shape of our NWs and recently reported in InAs NWs grown by molecular beam epitaxy (MBE). 9 This flux cancellation leads to an overestimation of B C , which in turn increases the value of c. A value of c % 1:4 was obtained for the MBE-grown NWs, which is close to our finding c % 2 for MOVPE-grown samples. The difference can be explained by the fact that the former were measured in the l T ) l u regime where c is expected to be smaller.…”

“…Confinement and interference effects start to dominate the electronic transport at cryogenic temperatures, and single-electron tunneling or phase coherent transport can be observed. [7][8][9] However, there are two factors inherent in the device geometry that greatly influence standard transport experiments and result in an experimental fingerprint for each nanowire. First, the high aspect ratio and enhanced surface conduction lead to an increased sensitivity to the environment.…”

Observation of coherent electron transport in self-catalysed InAs and InAs1–xSbx nanowires grown on silicon

“…The presence of both the constant rms(G B ) and B c demonstrates that the phase coherence length exceeds the contact separation below 2 K. This gives a value of 1.1 for the γ coefficient which will be used in the following to estimate the phase coherence length of the nanowires. This value is consistent with the 0.95 -2.0 range reported in the literature for InAs nanowires [32][33][34].…”

Aharonov-Bohm oscillations and electron gas transitions in hexagonal core-shell nanowires with an axial magnetic field

“…Observation of flat magnetoconductance when sweeping V g has not been reported in the transport measurements performed hitherto on hexagonal NWs under axial magnetic fields [9,[16][17][18]. However, in these works the electron density was normally modulated by a back-gate instead of a gateall-around.…”

“…This boosts their prospective applications in spintronics [6], even at relatively high temperature [7]. Furthermore, in this narrow-gap material, the Fermi energy, E F , is pinned by surface states above the conduction-band edge [8], leading to an accumulation of electrons at the NW surface and facilitating the fabrication of Ohmic contacts [1,9].…”