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Polarization-dependent vibrational shifts on dielectric substrates

2020, Yang, C., Wang, W., Nefedov, A., Wang, Y., Mayerhöfer, T.G., Wo¨ll, C.

The interaction of light with matter at surfaces of dielectrics strongly depends on polarization. Here, we present the first infrared spectroscopic evidence for significant polarization effects in the spectroscopic detection of adsorbate vibrational frequencies. In addition to much larger peak intensities for p-polarized light relative to s-polarization, a small but distinct blue shift was identified for CO adsorbed at the surfaces of two prototype dielectric substrates, CeO2(111) and CaCO3(10.4). A simulation using a layer model yields very good agreement with experiment.

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Atomically precise semiconductor-graphene and hBN interfaces by Ge intercalation

2015, Verbitskiy, N.I., Fedorov, A.V., Profeta, G., Stroppa, A., Petaccia, L., Senkovskiy, B., Nefedov, A., Wöll, C., Usachov, D.Yu., Vyalikh, D.V., Yashina, L.V., Eliseev, A.A., Pichler, T., Grüneis, A.

The full exploration of the potential, which graphene offers to nanoelectronics requires its integration into semiconductor technology. So far the real-world applications are limited by the ability to concomitantly achieve large single-crystalline domains on dielectrics and semiconductors and to tailor the interfaces between them. Here we show a new direct bottom-up method for the fabrication of high-quality atomically precise interfaces between 2D materials, like graphene and hexagonal boron nitride (hBN), and classical semiconductor via Ge intercalation. Using angle-resolved photoemission spectroscopy and complementary DFT modelling we observed for the first time that epitaxially grown graphene with the Ge monolayer underneath demonstrates Dirac Fermions unaffected by the substrate as well as an unperturbed electronic band structure of hBN. This approach provides the intrinsic relativistic 2D electron gas towards integration in semiconductor technology. Hence, these new interfaces are a promising path for the integration of graphene and hBN into state-of-the-art semiconductor technology.