Dresden 2026 – scientific programme
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QI: Fachverband Quanteninformation
QI 14: Quantum Information Poster Session
QI 14.23: Poster
Wednesday, March 11, 2026, 18:00–21:00, P4
Si/SiGe interfaces for scalable qubit devices - a depth resolved HAXPES study — •Nathalie Niederbudde1, Andreas Fuhrberg1, Denny Dütz2, Andrej Gloskovskii3, Christoph Schlueter3, Lars R. Schreiber2, and Martina Müller1 — 1Universität Konstanz — 2RWTH Aachen University — 3DESY, Hamburg, Germany
An ongoing challenge in quantum physics research is optimizing the performance of silicon-based spin qubits. These devices use the intrinsic spin of electrons as logic states. The electron location is electrostatically controlled by biased gate pattern on top of the device. A common spin qubit platform compatible with industrial processes is based on SiGe/Si/SiGe heterostructures, where the electron is trapped in the strained Si layer. To achieve reliable control of the trapping potential, defects occurring mainly at the Si-capping layer and the amorphous gate-oxide must be explored, studied and minimized.
This study investigates an Al2O3/Si/SiGe-qubit structure using hard X-ray photoelectron spectroscopy (HAXPES) with synchrotron radiation of 2.8 & 6 keV at beamline P22, DESY. The influence of thermal annealing typical for device fabrication on the Si capping layer is analysed. Si oxide formation is observed independently of annealing, with a thicker oxide layer forming in the annealed sample and an additional shift in binding energies. Additional oxidation states are found close to the Si/Al2O3 interface. Although the entire Si layer is thought to be oxidized, no Ge oxide was detected. This study improves our understanding of the influence of qubit preparation processes.
Keywords: SiGe qubits; HAXPES; XPS; synchrotron radiation; oxidation