11/11/2024 at 15.00, Room Conversi, Dip. Fisica Building Marconi
In recent years, direct band gap Germanium-Tin (GeSn) semiconductors have gained major attention for the monolithic integration of infrared emitters and detectors on a Si wafer.[1] A variety of GeSn infrared sensing and imaging technologies are now being developed using industrial-compatible fabrication processes. In this presentation, we will discuss the recent advances in the epitaxy of GeSn semiconductors in both thin film and nanowire geometries, and their integration in photodetectors, LEDs, and lasers on Si operating in the short- and mid-wave infrared at room temperature.[2-4]
In addition to the high potential for integration in photonic technologies, GeSn quantum materials have been proposed for the design of novel solid-state qubits architectures based on holes rather than electrons.[5-6] Tensile-strained Ge/GeSn quantum wells (QWs) grown on a Si wafer result in a confined 2D hole gas with light-hole (LH) states lying above the heavy-hole (HH) ones. The LH-based nature of the Ge/GeSn QW is in striking difference with canonical Ge/SiGe QWs where HH are confined.[7] Strategies to engineer both LH and HH spin qubits using Sn-based heterostructures will be discussed and the experimental results compared with HH Ge/SiGe QWs to enrich the available architectures for solid-state qubits on Si. Lastly, the epitaxial growth of isotopically-purified 70Ge quantum wells will be demonstrated and their structural properties analyzed down to the atomic level.[8] Removing the 73Ge nuclear spin will suppress the hyperfine interaction and improve the coherence time in nuclear spin-free Ge qubits.
[1] O. Moutanabbir, et al. Appl. Phys. Lett. 118, 110502 (2021).
[2] M.R.M. Atalla, et al. ACS Phot. 9, 4 (2022).
[3] Y. Zhou, et al. Optica 7, 8 (2020).
[4] L. Luo, et al. ACS Phot. 9, 3 (2022).
[5] S. Assali, et al., Adv. Mater. 34, 2201192 (2022).
[6] P. Del Vecchio, O. Moutanabbir, Phys. Rev. B 107, L161406 (2023).
[7] G. Scappucci, et al., Nature Reviews Mater. 6, 926-943 (2021).
[8] O. Moutanabbir, et al. Adv. Mater. 2023, 2305703 (2023).
Dr. Assali received his PhD in Physics from Eindhoven University of Technology on III-V semiconductor nanowires. He then worked as a research associate at Polytechnique Montreal to develop GeSn infrared materials and devices. Currently, he is a permanent researcher at CEA Grenoble where he establishes Sn-based infrared photonics and quantum devices.