Understanding the nature of metal-graphene contacts: A theoretical and experimental study

http://www.gianlucafiori.org/articles/IEDM_2015_Contacts.pdfIn this paper we propose a theoretical and experimental study of the nature of metal-graphene contacts. We use ab-initio simulations and semi-analytical modeling to derive and validate a simple two-parameter model of metal-graphene contacts. Such findings are supported by experimental results for large samples of different types of metal-graphene contacts

Multi-pronged proteomic analysis to study the glioma pathobiology using cerebrospinal fluid samples

PurposeGliomas are one of the most aggressive and lethal brain tumors arising from neoplastic transformation of astrocytes and oligodendrocytes. A comprehensive quantitative analysis of proteome level differences in cerebrospinal fluid (CSF) across different grades of gliomas for a better understanding of glioma pathobiology is carried out. Experimental designGlioma patients are diagnosed by radiology and histochemistry-based analyses. Differential proteomic analysis of high (n = 12) and low (n = 8) grade gliomas, and control (n = 3) samples is performed by using two complementary quantitative proteomic approaches; 2D-DIGE and iTRAQ. Further, comparative analysis of three IDH wild-type and five IDH mutants is performed to identify the proteome level differences between these two sub-classes. ResultsLevel of several proteins including haptoglobin, transthyretin, osteopontin, vitronectin, complement factor H and different classes of immunoglobulins are found to be considerably increased in CSF of higher grades of gliomas. Subsequent bioinformatics analysis indicated that many of the dysregulated CSF proteins are associated with metabolism of lipids and lipoproteins, complement and coagulation cascades and extracellular matrix remodeling in gliomas. Intriguingly, CSF of glioma patients with IDH mutations exhibite increased levels of multiple proteins involved in response to oxidative stress. Conclusion and clinical relevanceTo the best of our knowledge, this is the foremost proteome level investigation describing comprehensive proteome profiles of different grades of gliomas using proximal fluid (CSF); and thereby providing insights into disease pathobiology, which aided in identification of grade and sub-type specific alterations. Moreover, if validated in larger clinical cohorts, a panel of differentially abundant CSF proteins may serve as potential disease monitoring and prognostic markers for gliomas

Improved understanding of metal\u2013graphene contacts

Metal\u2013graphene (M\u2013G) contact resistance (RC) is studied through extensive experimental characterization,Monte\u2013Carlo transport simulations and Density Functional Theory (DFT) analysis. We show that the back\u2013gate voltage dependence of RC cannot be explained only in terms of the resistance of the junction at the edge between contact and channel region. Experiments and DFT calculations indicate a consistent picture where both Ni andAu contacts have a M\u2013G distance larger than the minimum energy distance, and where the M\u2013G distance is crucial in determining the RC value

Contact resistance Study of “edge-contacted” metal-graphene interfaces

International audienceThe contact resistance RC of "edge-contacted" metal-graphene interfaces is systematically studied. Our experiments demonstrate a reduction of contact resistance by intentional patterning of graphene to create "edge contacts". The parameter space for different hole patterns in graphene is explored. The contact resistance is reduced from 1518 Omega mu m for structures without holes to 456 Omega mu m in structures with holes of 500 nm diameter everywhere under the contact. These values were achieved at the Dirac point, i.e. at the point of minimum carrier density in graphene and they correspond to a reduction of 70%. These results provide a clear path towards higher performance in graphene based electronic devices, which are often limited by unreliable and high RC

Improved understanding of metal–graphene contacts

Metal–graphene (M–G) contact resistance (RC) is studied through extensive experimental characterization,Monte–Carlo transport simulations and Density Functional Theory (DFT) analysis. We show that the back–gate voltage dependence of RC cannot be explained only in terms of the resistance of the junction at the edge between contact and channel region. Experiments and DFT calculations indicate a consistent picture where both Ni andAu contacts have a M–G distance larger than the minimum energy distance, and where the M–G distance is crucial in determining the RC value