Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 20: Poster IA (Ultrafast phenomena; Optical properties; Transport; Theory)

HL 20.19: Poster

Montag, 16. März 2015, 15:00–20:00, Poster B

Hall effect in an asymmetric ballistic cross junction — •Joeren von Pock¹, Ulrich Wieser¹, Thomas Hackbarth², and Ulrich Kunze¹ — ¹Lehrstuhl für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — ²DaimlerChrysler Forschungszentrum Ulm, D-89081 Ulm

Low-temperature (T = 4.2 K) Hall measurements up to B = 15 T are performed on a ballistic cross junction consisting of 220 nm wide channels on a high mobility Si/SiGe heterostructure (µ_2D = 18.3 m²V⁻¹s⁻¹, n_2D = 6.3· 10¹⁵ m⁻² at 1.4 K). A non-centrosymmetric Hall geometry is formed by a straight current channel and oblique voltage probes attached to the channel under 45^∘ in the same direction. A Pd gate electrode covers the whole structure. In the nonlinear transport regime (current I ≈ 1 µ A) at low magnetic fields (B ≤ 1 T) the absolute value of the Hall voltage depends on the current direction [1]. This is explained in terms of ballistic cyclotron orbits propagating into the oblique probe channels. Surprisingly, the polarity dependence persists up to magnetic fields up to B = 15 T, where the cyclotron diameter shrinks to 13 nm, which is less than the effective channel width.
U. Wieser et al., Physica E 40, 2179 (2008).