Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 19: Quantum dots and wires: Transport properties

HL 19.9: Talk

Tuesday, March 13, 2018, 11:45–12:00, A 151

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 excess noise was already found to be related to an electron’s transmission probability [1]. In this work, cross-correlated noise measurements are performed in etched Al_xGa_1-xAs/GaAs based ballistic quasi 1D quantum rings 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] Y. M. Blanter et al., Phys. Rep. 336, 1 (2000).