All entries for geraldine paulus

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Charge Transfer at Junctions of a Single Layer of Graphene and a Metallic Single Walled Carbon Nanotube

• Authors: G.L.C. Paulus, Q.H. Wang, Z.W. Ulissi, T.P. McNicholas, A. Vijayaraghavan, C.-J. Shih, Z. Jin, M.S. Strano
• Sponsorship: 2009 US Office of Naval Research Multi University Research Initiative (MURI) grant; DOE CSGF program, Institute of Soldier Nanotechnology

In this work we fabricate and study junction between a single walled carbon nanotube (SWNT) and a monolayer of graphene for the first time^[1]. A single layer graphene (SLG) sheet grown by chemical vapor deposition (CVD) is transferred onto a SiO₂/Si wafer with aligned CVD-grown SWNTs. Raman spectroscopy is used to identify metallic-SWNT/SLG junctions, and we report a method for spectroscopic deconvolution of the overlapping G peaks of the SWNT and the SLG by making use of the polarization dependence of the SWNT^[2]. A comparison of the Raman peak positions and intensities of the individual SWNT and graphene to those of the SWNT-graphene junction indicates an electron transfer of 1.12 x 10¹³ cm^-2 from the SWNT to the graphene. This direction of charge transfer is in agreement with the work functions of the SWNT and graphene^[3]. We find that the compression of the SWNT by the graphene increases the width of the radial breathing mode (RBM) peak from 3.6 +/-0.3 to 4.6+/-0.5 cm^-1 and that of the G peak from 13+/-1 to 18+/-1 cm^-1, in reasonable agreement with our molecular dynamics simulations. However, we conclude that the RBM and G peak position shifts are primarily due to charge transfer with minimal contributions from strain. With this method, we demonstrate the ability to dope graphene with nanometer resolution.

1. G.L.C. Paulus, Q.H. Wang, Z.W. Ulissi, T.P. McNicholas, A. Vijayaraghaan, C.-J. Shih, Z. Jin, M.S. Strano, “Charge transfer at junctions of a single layer of graphene and a metallic single walled carbon nanotube,” Small, vol. 9, no. 11, pp. 1954-1963, June 2013. [↩]
2. G.S. Duesberg, I. Loa, M. Burghard, K. Syassen, S. Roth, “Polarized raman spectroscopy on isolated single-wall carbon nanotubes,” Physical Review Letters, vol. 85, no. 25, pp. 5436-5439, December 2000. [↩]
3. V. Barone, J.E. Peralta, J. Uddin, G.E. Scuseria, Journal of Chemical Physics, vol. 124, no. 2, pp. 024709 (1-5), January 2006. [↩]