05 Fakultät Informatik, Elektrotechnik und Informationstechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/6
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Item Open Access Sharp MIR plasmonic modes in gratings made of heavily doped pulsed laser-melted Ge1-xSnx(2023) Berkmann, Fritz; Steuer, Oliver; Ganss, Fabian; Prucnal, Slawomir; Schwarz, Daniel; Fischer, Inga Anita; Schulze, JörgItem Open Access Plasmonic gratings from highly doped Ge1-ySny films on Si(2021) Berkmann, Fritz; Ayasse, Markus; Schlipf, Jon; Mörz, Florian; Weißhaupt, David; Oehme, Michael; Prucnal, Slawomir; Kawaguchi, Yuma; Schwarz, Daniel; Fischer, Inga Anita; Schulze, JörgPlasmonic modes in metal structures are of great interest for optical applications. While metals such as Au and Ag are highly suitable for such applications at visible wavelengths, their high Drude losses limit their usefulness at mid-infrared wavelengths. Highly n-doped Ge1-ySny alloys are interesting possible alternative materials for plasmonic applications in this wavelength range. Here, we investigate the use of highly n-doped Ge1-ySny films grown directly on Si by molecular beam epitaxy with varying Sn-content from 0% up to 7.6% for plasmonic grating structures. We compare plasma wavelengths and relaxation times obtained from electrical and optical characterization. While theoretical considerations indicate that the decreasing effective mass with increasing Sn content in Ge1-ySny films could improve performance for plasmonic applications, our optical characterization results show that the utilization of Ge1-ySny films grown directly on Si is only beneficial if material quality can be improved.Item Open Access Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting(2022) Steuer, Oliver; Schwarz, Daniel; Oehme, Michael; Schulze, Jörg; Mączko, Herbert; Kudrawiec, Robert; Fischer, Inga A.; Heller, René; Hübner, René; Khan, Muhammad Moazzam; Georgiev, Yordan M.; Zhou, Shengqiang; Helm, Manfred; Prucnal, SlawomirThe pseudomorphic growth of Ge1-xSnx on Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1-xSnx alloys. Therefore, efficient strain engineering is required. In this article, we present strain and band-gap engineering in Ge1-xSnx alloys grown on Ge a virtual substrate using post-growth nanosecond pulsed laser melting (PLM). Micro-Raman and x-ray diffraction (XRD) show that the initial in-plane compressive strain is removed. Moreover, for PLM energy densities higher than 0.5 J cm-2, the Ge0.89Sn0.11 layer becomes tensile strained. Simultaneously, as revealed by Rutherford Backscattering spectrometry, cross-sectional transmission electron microscopy investigations and XRD the crystalline quality and Sn-distribution in PLM-treated Ge0.89Sn0.11 layers are only slightly affected. Additionally, the change of the band structure after PLM is confirmed by low-temperature photoreflectance measurements. The presented results prove that post-growth ns-range PLM is an effective way for band-gap and strain engineering in highly-mismatched alloys.Item Open Access Ge-on-Si single-photon avalanche diode using a double mesa structure(2024) Wanitzek, Maurice; Schulze, Jörg; Oehme, MichaelItem Open Access Fabrication and characterization of n-type Ge1-xSnx- and Si1-x-yGeySnx-on-SOI junctionless transistors(2025) Steuer, Oliver; Ghosh, Sayantan; Schwarz, Daniel; Oehme, Michael; Lehmann, Sebastian; Hübner, René; Fowley, Ciarán; Erbe, Artur; Zhou, Shengqiang; Helm, Manfred; Cuniberti, Gianaurelio; Prucnal, Slawomir; Georgiev, Yordan M.AbstractGe1-xSnx and Si1-x-yGeySnx alloys are promising materials for future nanoelectronic applications owing to their high carrier mobilities and CMOS compatibility. However, ternary Si1-x-yGeySnx transistors have only theoretically been discussed, and there are only a few reports on lateral n-type Ge1-xSnx transistors to benchmark their material performance. The low equilibrium solid solubility of Sn in Si1-xGex (less than 1 at%) requires device fabrication processes at temperatures below the growth temperature of Si1-x-yGeySnx (x > equilibrium solubility) or at non-equilibrium conditions. Therefore, Si-based processes need to be adjusted according to the materials requirements. A relatively easy-to-fabricate device concept are junctionless field effect transistors, which operate as a gated resistor. In this work, we use Ge0.94Sn0.06 and Si0.14Ge0.80Sn0.06 grown on silicon-on-insulator substrates to fabricate and characterize lateral n-type Ge1-xSnx and SiyGe1-x-ySnx junctionless field effect transistors. The transistors were structurally characterized by top-view scanning electron microscopy and cross-sectional transmission electron microscopy. Electrical characterizations by transfer characteristics show the first working n-type Ge1-xSnx and Si1-x-yGeySnx hetero-nanowire transistors, achieving on/off-current ratios of up to eight orders of magnitude.