Suche nach „[A.] [Gahoi]“ hat 2 Publikationen gefunden
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    NachhaltigF: Angewandte Naturwissenschaften und WirtschaftsingenieurwesenS: TC Teisnach Sensorik


    M. König, Günther Ruhl, A. Gahoi, S. Wittman, T. Preis, J.-M. Batke, I. Costina, M. Lemme

    Accurate Graphene-Metal Junction Characterization

    IEEE Journal of the Electron Devices Society (J-EDS), vol. 7, pp. 219-226


    DOI: 10.1109/JEDS.2019.2891516

    Abstract anzeigen

    A reliable method is proposed for measuring specific contact resistivity (p C ) for graphenemetal contacts, which is based on a contact end resistance measurement. We investigate the proposed method with simulations and confirm that the sheet resistance under the metal contact (R SK ) plays an important role, as it influences the potential barrier at the graphene-metal junction. Two different complementary metal-oxide-semiconductor-compatible aluminum-based contacts are investigated to demonstrate the importance of the sheet resistance under the metal contact: the difference in R SK arises from the formation of insulating aluminum oxide (Al 2 O 3 ) and aluminum carbide (Al 4 C 3 ) interfacial layers, which depends on the graphene pretreatment and process conditions. Auger electron spectroscopy and X-ray photoelectron spectroscopy support electrical data. The method allows direct measurements of contact parameters with one contact pair and enables small test structures. It is further more reliable than the conventional transfer length method when the sheet resistance of the material under the contact is large. The proposed method is thus ideal for geometrically small contacts where it minimizes measurement errors and it can be applied in particular to study emerging devices and materials.

    NachhaltigF: Angewandte Naturwissenschaften und WirtschaftsingenieurwesenS: TC Teisnach Sensorik


    G. Lupina, J. Kitzmann, I. Costina, M. Lukosius, C. Wenger, A. Wolff, S. Vaziri, M. Östling, I. Pasternak, A. Krajewska, W. Strupinski, S. Kataria, A. Gahoi, M. Lemme, Günther Ruhl, G. Zoth, O. Luxenhofer, W. Mehr

    Residual Metallic Contamination of Transferred Chemical Vapor Deposited Graphene

    ACS Nano, vol. 9, no. 5, pp. 4776-4785


    DOI: 10.1021/acsnano.5b01261

    Abstract anzeigen

    Integration of graphene with Si microelectronics is very appealing by offering a potentially broad range of new functionalities. New materials to be integrated with the Si platform must conform to stringent purity standards. Here, we investigate graphene layers grown on copper foils by chemical vapor deposition and transferred to silicon wafers by wet etching and electrochemical delamination methods with respect to residual submonolayer metallic contaminations. Regardless of the transfer method and associated cleaning scheme, time-of-flight secondary ion mass spectrometry and total reflection X-ray fluorescence measurements indicate that the graphene sheets are contaminated with residual metals (copper, iron) with a concentration exceeding 1013 atoms/cm2. These metal impurities appear to be partially mobile upon thermal treatment, as shown by depth profiling and reduction of the minority charge carrier diffusion length in the silicon substrate. As residual metallic impurities can significantly alter electronic and electrochemical properties of graphene and can severely impede the process of integration with silicon microelectronics, these results reveal that further progress in synthesis, handling, and cleaning of graphene is required to advance electronic and optoelectronic applications.