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HL: Fachverband Halbleiterphysik

HL 22: Quantum dots and wires: Transport properties

HL 22.5: Vortrag

Dienstag, 2. April 2019, 15:00–15:15, H34

Excess noise in Al_xGa_1-xAs/GaAs based quantum rings — •Christian Riha¹, Sven S. Buchholz¹, Olivio Chiatti¹, Dirk Reuter², Andreas D. Wieck³, and Saskia F. Fischer¹ — ¹Novel Materials Group, Humboldt-Universität zu Berlin, D-12489 Berlin — ²Optoelektronische Materialien und Bauelemente, Universität Paderborn, D-33098 Paderborn — ³Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum

The characteristics of electrical noise provide various information about an electronic system. In ballistic 1D quantum devices [1] excess noise was already found to be related to an electron’s transmission probability. In this work, cross-correlated noise measurements are performed in etched Al_xGa_1-xAs/GaAs based ballistic quasi 1D quantum rings [2] at a bath temperature of T_bath= 4.2 K in equilibrium. The measured white noise exceeds the thermal noise expected from the measured electron temperature T_e and the electrical resistance R of the devices. This excess noise decreases as T_bath increases and is not observable anymore at T_bath≥ 12 K. Furthermore, a reduction of the excess noise is observed when one arm of a quantum ring becomes electrically non-conducting. This excess noise is not observed in 1D-constrictions that share a comparable length and width with the quantum rings. The results suggest that the excess noise is a result of electron interference in the quantum ring.

[1] C. Riha et al., Phys. Status Solidi A 213, 571 (2016).

[2] C. Riha et al., Appl. Phys. Lett. 106, 083102 (2015).