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HL: Fachverband Halbleiterphysik

HL 46: Quantum Dots and Wires: Transport

HL 46.12: Vortrag

Mittwoch, 24. März 2010, 17:00–17:15, H17

Electronic phase coherence in InAs nanowires — •Christian Blömers, Mihail Ion Lepsa, Steffi Lenk, Hans Lüth, Thomas Schäpers, and Detlev Grützmacher — Institute of Bio- and Nanosystems (IBN-1) and JARA - Fundamentals of Future Information Technology, Forschungszentrum Jülich GmbH, D-52425 Jülich

We report on magnetotransport measurements on InAs nanowires grown by molecular beam epitaxy. Among the III-V semiconductor materials, InAs is particularly interesting because of its low direct band gap and its low effective mass. Additionally InAs is known to show a strong quantum confinement in devices of mesoscopic dimensions. A well known quantum effect revealed by magnetotransport measurements at low temperatures are the universal conductance fluctuations (UCF), resulting from electron interference. By analyzing the UCFs it is possible to draw conclusions about the phase coherence length of the electrons in the device. In the special case of a magnetic field in parallel to the wire, Altshuler-Aronov-Spivak oscillations were found in lithographically defined InAs columns. These oscillations are known to result from the surface 2DEG, which is present in those columns. In contrast the present InAs wires do not show this behavior. The explanation is given in terms of the high density of stacking faults, which were observed in transmission electron microscopy. The stacking faults are due to transitions between wurtzite and zincblende structure. The wurtzite segments are origins of polarization charges which most probably mask the effect of surface states, being the reason for the surface 2DEG.