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Suche nach „[I.] [Costina]“ hat 4 Publikationen gefunden
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    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ Spiegelau

    Zeitschriftenartikel

    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

    2019

    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.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ Spiegelau

    Zeitschriftenartikel

    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

    2015

    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.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ Spiegelau

    Zeitschriftenartikel

    C. Baristiran Kaynak, M. Lukosius, I. Costina, B. Tillack, C. Wenger, Günther Ruhl, T. Blomberg

    Enhanced leakage current behavior of Sr2Ta2O7-x/SrTiO3 bilayer dielectrics for metal-insulator-metal capacitors

    Thin Solid Films, vol. 519, no. 17, pp. 5734-5739

    2011

    DOI: 10.1016/j.tsf.2011.01.001

    Abstract anzeigen

    Metal–Insulator–Metal (MIM) capacitors are one of the most essential components of radio frequency devices and analog/mixed-signal integrated circuits. In order to obtain high capacitance densities in MIM devices, high-k materials have been considered to be promising candidates to replace the traditional insulators. The challenging point is that the dielectric material must demonstrate high capacitance density values with low leakage current densities. In this work, SrTiO3 based MIM capacitors have been investigated and the electrical performance of the devices have been optimized by using bilayered systems of Sr2Ta2O7−x/SrTiO3 with different thicknesses of Sr2Ta2O7−x. Sputtering X-Ray photoelectron spectroscopy (XPS) measurements have been applied to investigate the interfaces between the thin film constituents of the MIM stacks. The optimized bilayered system provides a leakage current density of 8∗10− 8 A/cm2 at 2 V (bottom electrode injection) and a high capacitance density of 13 fF/μm2.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenTAZ Spiegelau

    Zeitschriftenartikel

    C. Baristiran Kaynak, M. Lukosius, I. Costina, B. Tillack, C. Wenger, Günther Ruhl, S. Rushworth

    Investigations of thermal annealing effects on electrical and structural properties of SrTaO based MIM capacitor

    Microelectronic Engineering, vol. 87, no. 12, pp. 2561-2564

    2010

    DOI: 10.1016/j.mee.2010.07.015

    Abstract anzeigen

    The annealing effects on dielectric and electrode materials in Ti/SrTaO/TaN/TiN/Ti/Si metal–insulator–metal (MIM) capacitors were studied. The electrical and structural properties were investigated after subjecting the samples to annealing temperatures of 500 °C, 700 °C and 900 °C. The electrical results revealed that the dielectric constant (k value) of Sr–Ta–O increased from 18 to 50 with increasing annealing temperature. This improvement in k value can be associated to the crystallization of dielectric layer. However, the leakage current density increased several orders of magnitudes with increase of the annealing temperatures. This observation was attributed to crystallization of dielectric, degradation of TaN electrode and out-diffusion of Si from the substrate.