Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting

article Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting devices published yes Maksim Borovkov author 1fd0975f-8b61-11ed-b69e-d149334f28c5 Yona A Schell author fe39122d-06bb-11ec-a33b-9e22b40e40a5 Dina Sokolova author 2d2d62f8-72f0-11ef-b75a-8ec3e8a60032 Kevin Etienne Robert Roux author 53f93ea2-803f-11ed-ab7e-b283135794ef Paul Falthansl-Scheinecker author 85b43b21-15b2-11ec-abd3-e2c252cc2285 Giorgio Fabris author 298cf6f3-1ff6-11ee-9fa6-d94cfa0b3352 Devashish C Shah author de191434-4e7e-11ef-bf4b-9a056fc19fc30009-0007-5829-7707 Jaime Saez Mollejo author e0390f72-f6e0-11ea-865d-862393336714 Rodolfo Previdi author bc4ea1dc-00ce-11ec-8a4e-b325ca8b9876 Inas Taha author Aziz Genç author Jordi Arbiol author Stefano Calcaterra author Afonso De Cerdeira Oliveira author Daniel Chrastina author Giovanni Isella author Anton Bubis author 1f6212b5-f795-11ec-9c0c-de4780302890 Georgios Katsaros author 38DB5788-F248-11E8-B48F-1D18A9856A870000-0001-8342-202X GeKa department GradSch department NanoFab department Quantum bits with Kitaev Transmons project Center for Correlated Quantum Materials and Solid State Quantum Systems: Conventional and unconventional topological superconductors project Superconducting spin qubits in planar Ge project Merging spin and superconducting qubits in planar Ge project Realization and Manipulation of a Planar hybrid superconducting Andreev spin qubit in Germanium project Planar germanium is currently the only semiconducting platform where high-coherence spin qubits and proximity-induced superconductivity have each been demonstrated. Recent research into spin qubits in Ge/SiGe heterostructures has focused on increasing the thickness of the SiGe capping layer, reporting improvements in the electrostatic noise levels. Meanwhile, heterostructures with thinner capping layers remain rather unexplored, despite the potential advantages for proximity-induced superconductivity. Here, we study a Ge/SiGe heterostructure with a thin SiGe cap d - 4nm and investigate its viability to host low-noise quantum dots. To keep the thermal budget compatible with superconducting layers, low-temperature oxide deposition processes were developed and implemented for the gate dielectrics. The charge noise level of the fabricated devices is estimated to be 1.8 +- 1.0 μeV/ square HZ⁠, comparable to devices fabricated on shallow heterostructures (⁠ d - 20nm⁠) with high-temperature deposited oxides. Low charge noise levels, together with the straightforward integration of superconductors, make this heterostructure an attractive platform for prototyping hybrid semiconducting–superconducting devices. AIP Publishing2026 eng Applied Physics Letters 0003-6951 1077-3118 2602.2136310.1063/5.0333142 1293 https://research-explorer.ista.ac.at/record/22242 Borovkov, M., Schell, Y. A., Sokolova, D., Roux, K. E. R., Falthansl-Scheinecker, P., Fabris, G., … Katsaros, G. (2026). Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting devices. Applied Physics Letters. AIP Publishing. <a href="https://doi.org/10.1063/5.0333142">https://doi.org/10.1063/5.0333142</a> Borovkov, Maksim, et al. “Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures for Prototyping Hybrid Semiconducting–Superconducting Devices.” Applied Physics Letters, vol. 129, no. 3, 033505, AIP Publishing, 2026, doi:<a href="https://doi.org/10.1063/5.0333142">10.1063/5.0333142</a>. M. Borovkov et al., “Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting devices,” Applied Physics Letters, vol. 129, no. 3. AIP Publishing, 2026. Borovkov M, Schell YA, Sokolova D, et al. Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting devices. Applied Physics Letters. 2026;129(3). doi:<a href="https://doi.org/10.1063/5.0333142">10.1063/5.0333142</a> M. Borovkov, Y.A. Schell, D. Sokolova, K.E.R. Roux, P. Falthansl-Scheinecker, G. Fabris, D.C. Shah, J. Saez Mollejo, R. Previdi, I. Taha, A. Genç, J. Arbiol, S. Calcaterra, A.D.C. Oliveira, D. Chrastina, G. Isella, A. Bubis, G. Katsaros, Applied Physics Letters 129 (2026). Borovkov, Maksim, Yona A Schell, Dina Sokolova, Kevin Etienne Robert Roux, Paul Falthansl-Scheinecker, Giorgio Fabris, Devashish C Shah, et al. “Low-Noise Quantum Dots in Ultra-Shallow Ge/SiGe Heterostructures for Prototyping Hybrid Semiconducting–Superconducting Devices.” Applied Physics Letters. AIP Publishing, 2026. <a href="https://doi.org/10.1063/5.0333142">https://doi.org/10.1063/5.0333142</a>. Borovkov M, Schell YA, Sokolova D, Roux KER, Falthansl-Scheinecker P, Fabris G, Shah DC, Saez Mollejo J, Previdi R, Taha I, Genç A, Arbiol J, Calcaterra S, Oliveira ADC, Chrastina D, Isella G, Bubis A, Katsaros G. 2026. Low-noise quantum dots in ultra-shallow Ge/SiGe heterostructures for prototyping hybrid semiconducting–superconducting devices. Applied Physics Letters. 129(3), 033505. 226192026-08-02T22:01:53Z2026-08-03T11:08:39Z