Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 20: Poster IA (Ultrafast phenomena; Optical properties; Transport; Theory)
HL 20.18: Poster
Monday, March 16, 2015, 15:00–20:00, Poster B
Asymmetric Hall cross junction — •Michael Szelong1, Arne Ludwig2, Andreas D. Wieck2, and Ulrich Kunze1 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — 2Angewandte Festkörperphysik, Ruhr-Universtät Bochum
We are analysing the influence of a geometrical asymmetry in a cross junction on Hall voltage in ballistic linear and nonlinear transport regime in a perpendicular magnetic field of up to 15 T. The cross junction consists of a straight current channel while two voltage probes merge into the middle of the current channel at an angle of 45∘. All four emerging branches have the same length of 900 nm and the same width of 330 nm. A top-gate has not been processed to prevent threshold voltage shifts during measurements. The device has been processed on a high-mobility GaAs/AlGaAs heterostructure with a two-dimensional electron density of n = 4.1 · 1011 cm−2 and a mobility of µn = 5.5 · 105 cm2/Vs, both at 4.2 K, resulting in an elastic mean free path of 5.8 µm.
A current through the current channel induces, with application of a perpendicular magnetic field, a Hall voltage in the 45-degree branches which is expected to be current polarity dependent, larger where electrons can easier enter the tilted branches, smaller in the opposite case. It is found that in non-linear regime this expectation is met whereas in weak non-linear regime it is sometimes turned upside down.