Browsing by Author "Schlipf, Jon"

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    Photonic-plasmonic mode coupling in nanopillar Ge-on-Si PIN photodiodes
    (2021) Augel, Lion; Schlipf, Jon; Bullert, Sergej; Bürzele, Sebastian; Schulze, Jörg; Fischer, Inga A.
    Incorporating group IV photonic nanostructures within active top-illuminated photonic devices often requires light-transmissive contact schemes. In this context, plasmonic nanoapertures in metallic films can not only be realized using CMOS compatible metals and processes, they can also serve to influence the wavelength-dependent device responsivities. Here, we investigate crescent-shaped nanoapertures in close proximity to Ge-on-Si PIN nanopillar photodetectors both in simulation and experiment. In our geometries, the absorption within the devices is mainly shaped by the absorption characteristics of the vertical semiconductor nanopillar structures (leaky waveguide modes). The plasmonic resonances can be used to influence how incident light couples into the leaky modes within the nanopillars. Our results can serve as a starting point to selectively tune our device geometries for applications in spectroscopy or refractive index sensing.
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    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, Jörg
    Plasmonic 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.
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    Raman shifts in MBE‐grown SixGe1 - x - ySny alloys with large Si content
    (2021) Schlipf, Jon; Tetzner, Henriette; Spirito, Davide; Manganelli, Costanza L.; Capellini, Giovanni; Huang, Michael R. S.; Koch, Christoph T.; Clausen, Caterina J.; Elsayed, Ahmed; Oehme, Michael; Chiussi, Stefano; Schulze, Jörg; Fischer, Inga A.
    We examine the Raman shift in silicon-germanium-tin alloys with high silicon content grown on a germanium virtual substrate by molecular beam epitaxy. The Raman shifts of the three most prominent modes, Si-Si, Si-Ge, and Ge-Ge, are measured and compared with results in previous literature. We analyze and fit the dependence of the three modes on the composition and strain of the semiconductor alloys. We also demonstrate the calculation of the composition and strain of SixGe1 - x - ySny from the Raman shifts alone, based on the fitted relationships. Our analysis extends previous results to samples lattice matched on Ge and with higher Si content than in prior comprehensive Raman analyses, thus making Raman measurements as a local, fast, and nondestructive characterization technique accessible for a wider compositional range of these ternary alloys for silicon‐based photonic and microelectronic devices.