Dresden 2017 – wissenschaftliches Programm
HL 25.1: Poster
Montag, 20. März 2017, 15:00–19:00, P2-OG2
In-situ metal deposition for low contact resistance on n-type ZnSe — •Johanna Janßen1, Torsten Rieger1, Arne Hollmann2, Lars Schreiber2, and Alexander Pawlis1 — 1Peter Grünberg Institute 9 and JARA-FIT, Forschungszentrum Jülich, 52425 Jülich, Germany — 2JARA Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany
As promising for quantum computing, electron spin qubits realized in electrostatically-defined quantum dots (QDs) were studied in GaAs and Si systems. Our goal is to define QDs in the 2D electron gas of ZnSe/(ZnMg)Se quantum wells, as ZnSe combines the advantages of both systems, a direct band gap and nuclear spin-free host lattice. An important parameter is the n-doping profile of ZnSe. We use ex-situ implantation of Fluorine donors to provide quantitative and spatial control of the doping concentration. However, the main challenge is to fabricate ohmic contacts on n-ZnSe. Low contact resistance and a linear current/voltage characteristic even at low temperatures (100 mK) are crucial for charge-based read-out of the QDs. In the context of studies on ZnSe for optoelectronics, the contact metals Al, Mg and In have shown to be suitable candidates for contact fabrication.
Here, we report our studies on the transport characteristics through as-grown ZnSe layers for different doping concentrations, contact metals, and processing techniques such as surface etching or thermal activation. Additional to the mostly performed ex-situ metallization processes, we deposited the metal in-situ to avoid surface oxidation, thus reducing the contact resistance.