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Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Poster I: Devices, Quantum Dots and Quantum Wires

HL 31.35: Poster

Tuesday, March 23, 2010, 18:30–20:30, Poster D1

Investigations of the conductance anomaly in strongly confined Si/SiGe quantum wires — •J. von Pock1, D. Salloch1, G. Qiao1, U. Wieser1, U. Kunze1, and T. Hackbarth21Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — 2DaimlerChrysler Forschungszentrum Ulm, D-89081 Ulm

We investigate the influence of temperature and high parallel magnetic field (B≤ 15  T) on a conductance anomaly observed below the first conductance plateau at G0 = 4 e2/h in Si/SiGe quantum wires. The quantum wires are fabricated from a high-mobility Si/SiGe heterostructure with an electron density of n=8.4· 1011 cm−2 and a mobility of µ=207,000  cm2(Vs)−1 at 4.2 K. The constriction of the wires is realised by an etch transfer in a low-damage CF4/O2 plasma, which provides a strong 1D confinement. The linear transport measurements are performed in a temperature range between 400  mK and 4.2 K. Besides the first regular conductance plateau at G0 an additional anomal plateau is observed near 0.6  G0 at B = 0  T. With increasing magnetic field the anomal plateau shifts to 0.5  G0 indicating the Zeeman splitting. Our results agree well with the behaviour of the 0.7 anomaly reported in AlGaAs/GaAs quantum point contacts and quantum wires [1]. For T= 500  mK we do not observe a zero-bias anomaly [2] in the subband spectroscopy around the conductance anomaly.
[1] K. J. Thomas et al., Phys. Rev. Lett. 77, 135 (1996)
[2] S. M. Cronenwett et al., Phys. Rev. Lett. 88, 226805 (2002)

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