Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 15: Quantum Dots and Wires: Fabrication and Devices
HL 15.5: Vortrag
Montag, 7. März 2016, 15:45–16:00, H16
Electrostatically defined quantum dots in undoped Si/SiGe heterostructures — •Floyd Schauer1, Christian Neumann1, Christian Fritsch1, Sebastian Schwägerl1, Simon Pfaehler1, Dieter Weiss1, Kentarou Sawano2, and Dominique Bougeard1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany — 2Advanced Research Laboratories, Tokio City University, Japan
Two-dimensional electron systems (2DES) in undoped heterostructures represent a promising building block for the development of electrostatically defined spin qubits. Omitting the dopants in the heterostructure eliminates fluctuating charge traps due to ionized impurities. The hyperfine interaction with the nuclear spin bath being a dominant qubit decoherence mechanism, Si/SiGe heterostructures have been receiving steadily increasing attention for building devices almost free of nuclear spin carrying isotopes.
In this contribution, we present the realization of capacitively-induced Si/SiGe Quantum Dot (QD) devices. A global top gate is used to accumulate electrons and induce a 2DES in the undoped Si quantum well via the field effect. We examine the capacitive coupling between surface gates and the 2DES as well as remaining charge noise sources in these undoped structures. A second gate layer in the devices allows to locally deplete the 2DES and to form QDs: we discuss the operation in the single QD regime.