Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 95: Poster IV B (Quantum dots and wires: Prepration, characterization, optical properties, and transport)
HL 95.28: Poster
Donnerstag, 19. März 2015, 14:00–20:00, Poster B
Signal addition in a dual-stage ballistic rectifier — •Joeren von Pock1, Sandra Rudnik1, Ulrich Wieser1, Thomas Hackbarth2, and Ulrich Kunze1 — 1Lehrstuhl für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — 2DaimlerChrysler Forschungszentrum Ulm, D-89081 Ulm
We investigate a ballistic rectifier consisting of 220 nm wide channels on a high mobility Si/SiGe heterostructure (µ2D = 18.3 m2 V−1 s−1, n2D = 6.3 · 1015 m−2 at 1.4 K). The rectifier geometry is formed by a straight voltage stem with contacts U and L and two pairs of injector branches (contacts 1-2 and 3-4) inclined with respect to the stem by 45∘. A Pd gate electrode covers the whole structure. At T = 4.2 K, under gate voltages VG ≥ 0.3 V solely ballistic transport determines the output voltage [1]. Each of the rectifier stages nearly exhibit a parabolic characteristic, i.e. VUL,ij = (αij · Iij)2, where ij refers to the contacts 12 or 34, respectively, and α12 ≈ α34 represents the individual rectifier sensitivities. If the injector pairs are separated by at least 450 nm the individual output voltages add up, VUL,tot = VUL,12 + VUL,34. At smaller separation VUL,tot exceeds the sum by up to 80%. We interpret this synergy gain by a gradual transition from voltage to current addition. Pure current addition should occur if both injector pairs are connected to the stem at the same position leading to VUL,tot = (α12 · I12 + α34 · I34)2, which is twice that of pure voltage addition.
D. Salloch et al., Appl. Phys. Lett. 94, 203503 (2009).