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Angle-dependent magnetotransport in GaAs/InAs core/shell nanowires.

Haas F, Wenz T, Zellekens P, Demarina N, Rieger T, Lepsa M, Grützmacher D, Lüth H, Schäpers T - Sci Rep (2016)

Bottom Line: These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell.Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles.We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

View Article: PubMed Central - PubMed

Affiliation: Peter Grünberg Institute 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

ABSTRACT
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov-Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

No MeSH data available.


Related in: MedlinePlus

(a) Grown GaAs/InAs core/shell nanowire with colourized InAs shell. (b) TEM image showing Moiré fringes due to the overlap of the crystal lattices of GaAs and InAs. (c) High resolution TEM image of the crystal structure of the InAs shell near the interface to the GaAs core. Frank partial misfit dislocations (FPD) are observed, which induce a stacking fault. Furthermore, a rotational twin adopted from the crystal structure of the core is seen. (d) Sample A: GaAs/InAs core/shell nanowire with Ti/Au contacts. (e) Definition of the angle of rotation γ. For γ = 0°, the magnetic field is oriented parallel to the nanowire axis.
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f1: (a) Grown GaAs/InAs core/shell nanowire with colourized InAs shell. (b) TEM image showing Moiré fringes due to the overlap of the crystal lattices of GaAs and InAs. (c) High resolution TEM image of the crystal structure of the InAs shell near the interface to the GaAs core. Frank partial misfit dislocations (FPD) are observed, which induce a stacking fault. Furthermore, a rotational twin adopted from the crystal structure of the core is seen. (d) Sample A: GaAs/InAs core/shell nanowire with Ti/Au contacts. (e) Definition of the angle of rotation γ. For γ = 0°, the magnetic field is oriented parallel to the nanowire axis.

Mentions: GaAs/InAs core/shell nanowires were grown using a self-assisted approach by molecular beam epitaxy, without using a foreign growth catalyst such as gold and without addition of dopants8. The growth was carried out on GaAs (111)B growth substrates covered by a thin layer of oxide, which forms nanometer sized pinholes. Within these holes Ga-droplets were created, which act as catalyst for the growth of the GaAs nanowire cores. In the second growth step, the GaAs nanowire cores were overgrown with an InAs shell. Both the GaAs nanowire core as well as the InAs shell have a hexagonal geometry. A typical example of such a GaAs/InAs core/shell nanowire can be seen in Fig. 1(a).


Angle-dependent magnetotransport in GaAs/InAs core/shell nanowires.

Haas F, Wenz T, Zellekens P, Demarina N, Rieger T, Lepsa M, Grützmacher D, Lüth H, Schäpers T - Sci Rep (2016)

(a) Grown GaAs/InAs core/shell nanowire with colourized InAs shell. (b) TEM image showing Moiré fringes due to the overlap of the crystal lattices of GaAs and InAs. (c) High resolution TEM image of the crystal structure of the InAs shell near the interface to the GaAs core. Frank partial misfit dislocations (FPD) are observed, which induce a stacking fault. Furthermore, a rotational twin adopted from the crystal structure of the core is seen. (d) Sample A: GaAs/InAs core/shell nanowire with Ti/Au contacts. (e) Definition of the angle of rotation γ. For γ = 0°, the magnetic field is oriented parallel to the nanowire axis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835758&req=5

f1: (a) Grown GaAs/InAs core/shell nanowire with colourized InAs shell. (b) TEM image showing Moiré fringes due to the overlap of the crystal lattices of GaAs and InAs. (c) High resolution TEM image of the crystal structure of the InAs shell near the interface to the GaAs core. Frank partial misfit dislocations (FPD) are observed, which induce a stacking fault. Furthermore, a rotational twin adopted from the crystal structure of the core is seen. (d) Sample A: GaAs/InAs core/shell nanowire with Ti/Au contacts. (e) Definition of the angle of rotation γ. For γ = 0°, the magnetic field is oriented parallel to the nanowire axis.
Mentions: GaAs/InAs core/shell nanowires were grown using a self-assisted approach by molecular beam epitaxy, without using a foreign growth catalyst such as gold and without addition of dopants8. The growth was carried out on GaAs (111)B growth substrates covered by a thin layer of oxide, which forms nanometer sized pinholes. Within these holes Ga-droplets were created, which act as catalyst for the growth of the GaAs nanowire cores. In the second growth step, the GaAs nanowire cores were overgrown with an InAs shell. Both the GaAs nanowire core as well as the InAs shell have a hexagonal geometry. A typical example of such a GaAs/InAs core/shell nanowire can be seen in Fig. 1(a).

Bottom Line: These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell.Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles.We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

View Article: PubMed Central - PubMed

Affiliation: Peter Grünberg Institute 9, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.

ABSTRACT
We study the impact of the direction of magnetic flux on the electron motion in GaAs/InAs core/shell nanowires. At small tilt angles, when the magnetic field is aligned nearly parallel to the nanowire axis, we observe Aharonov-Bohm type h/e flux periodic magnetoconductance oscillations. These are attributed to transport via angular momentum states, formed by electron waves within the InAs shell. With increasing tilt of the nanowire in the magnetic field, the flux periodic magnetoconductance oscillations disappear. Universal conductance fluctuations are observed for all tilt angles, however with increasing amplitudes for large tilt angles. We record this evolution of the electron propagation from a circling motion around the core to a diffusive transport through scattering loops and give explanations for the observed different transport regimes separated by the magnetic field orientation.

No MeSH data available.


Related in: MedlinePlus