Berlin 2024 – scientific programme

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QI: Fachverband Quanteninformation

QI 18: Poster II

QI 18.27: Poster

Wednesday, March 20, 2024, 11:00–14:30, Poster A

Characterization of Paramagnetic States in Substrates for Transmon Qubits — •Michael Göldl^1,3, Niklas Bruckmoser^2,3, Leon Koch^2,3, Stefan Filipp^2,3, and Martin S. Brandt^1,3 — ¹Walter Schottky Institut, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany — ²Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meißner-Straße 8, 85748 Garching, Germany — ³School of Natural Science, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany

Electrically Detected Magnetic Resonance (EDMR) is a highly sensitive technique to detect paramagnetic impurities and defects in semiconductors. Defects like the P_b0 defect at the Si/SiO₂ interface are such paramagnetic states and act as recombination centers for excess charge carriers which can be detected as a decrease in photoconductivity. Since both P_b0 and charge carriers such as electrons in the conduction band have spin, this recombination is governed by the Pauli exclusion principle. Using magnetic resonance, the spin signature of the defects as well as their concentration can be determined. Here, we present a study where we quantify the P_b0 defect densities in Si substrates used for for the manufacturing of superconducting transmon qubits and compare the EDMR results obtained after varying interface treatments of the substrate to coherence times observed for transmon qubits fabricated on similarly treated wafers.