Freiburg 2019 – wissenschaftliches Programm
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FM: Fall Meeting
FM 14: Quantum Computation: Hardware Platforms I
FM 14.4: Talk
Montag, 23. September 2019, 15:00–15:15, 3044
Low-temperature ohmic contacts to n-ZnSe for all-electrical quantum devices — •Felix Hartz1, Johanna Janßen2, Till Huckemann1, Malte Neul1, Lars R. Schreiber1, and Alexander Pawlis2 — 1JARA - Institute for Quantum Information, RWTH Aachen University, Germany — 2Peter Grünberg Institute 9 and JARA - FIT, Forschungszentrum Jülich GmbH, Germany
The most advanced semiconductor spin qubits are realized in gate defined quantum dots in 28Si. Qubit performance has been improved by isotopical purification and qubit integration in Si/SiGe heterostructures finally limited by spin valley splitting. ZnSe is an ideal host material for gate defined quantum dots as it has no valleys, provides a photonic link [1] and is potentially nuclear spin free after isotopical purification [2]. Prerequisite to all-electrical qubits are ohmic contacts to ZnSe operating at cryogenic temperatures that have not been realized so far. Here we present a complete analysis on ohmic contacts to n-type ZnSe. By in−situ Al metallisation of the ohmic contact without breaking ultra-high vacuum conditions, we avoid the natural ZnSe oxide and therefore achieve a record contact resistivity of (2.3±0.8)· 10−5 Ωcm2 at room temperature and (4±2)· 10−5 Ωcm2 at 4 K. We demonstrate local ohmic contacts combining the in−situ technique with selective regrowth yielding low resistivity contacts with (1.7±0.2)· 10−4 Ωcm2 also operating at 4 K ((1.4±0.4)· 10−3 Ωcm2). This allows for a new type of quantum devices such as gate defined quantum dots in ZnSe. [1] K. Sanaka ea., Nano Lett. (2012) [2] A. Pawlis ea., Appl. Electron. Mater. (2019)