Ytterbium Intercalation of Epitaxial Graphene Grown on Si-Face SiC
Author(s)
Somsakul Watcharinyanon1,
Leif I. Johansson1,
Chao Xia1,
Jan Ingo Flege2,
Axel Meyer2,
Jens Falta2,
Chariya Virojanadara1
Affiliation(s)
1 Department of Physics, Chemistry, and Biology, Linkoping University, Linkoping, Sweden. 2 Institute of Solid State Physics, University of Bremen, Bremen, Germany.
1 Department of Physics, Chemistry, and Biology, Linkoping University, Linkoping, Sweden. 2 Institute of Solid State Physics, University of Bremen, Bremen, Germany.
ABSTRACT
The rare-earth metal, ytterbium (Yb), was deposited on graphene grown on Si-face SiC, kept at room temperature. Yb was not found to intercalate, destroy or dope the graphene layer before subsequent heating, unlike alkali metals such as Li and Na. Our photoemission results reveal that heating to 300oC promotes Yb intercalation into the graphene-substrate interface. Real-time low energy electron microscopy (LEEM) measurements indicated intercalation to start at a sample temperature of around 220oC. In the intercalation process, Yb penetrates through the graphene and buffer layer and forms bonds to the silicon in the topmost SiC substrate bilayer, as indicated by the shifted components observed in the C 1s, Si 2p, and Yb 4f spectra. The Yb intercalation decouples the buffer layer from the substrate and transforms it into another graphene layer as manifested by the absence of buffer layer spots in the μ-LEED pattern and the appearance of an additional π band in the ARPES spectra, respectively. Moreover, the observed shift of the Dirac point down from the Fermi level by 1.9 eV indicates electron doping of the graphene layer upon Yb intercalation. The Yb intercalated graphene sample was found to be thermodynamically stable up to temperatures around 700oC.
The rare-earth metal, ytterbium (Yb), was deposited on graphene grown on Si-face SiC, kept at room temperature. Yb was not found to intercalate, destroy or dope the graphene layer before subsequent heating, unlike alkali metals such as Li and Na. Our photoemission results reveal that heating to 300oC promotes Yb intercalation into the graphene-substrate interface. Real-time low energy electron microscopy (LEEM) measurements indicated intercalation to start at a sample temperature of around 220oC. In the intercalation process, Yb penetrates through the graphene and buffer layer and forms bonds to the silicon in the topmost SiC substrate bilayer, as indicated by the shifted components observed in the C 1s, Si 2p, and Yb 4f spectra. The Yb intercalation decouples the buffer layer from the substrate and transforms it into another graphene layer as manifested by the absence of buffer layer spots in the μ-LEED pattern and the appearance of an additional π band in the ARPES spectra, respectively. Moreover, the observed shift of the Dirac point down from the Fermi level by 1.9 eV indicates electron doping of the graphene layer upon Yb intercalation. The Yb intercalated graphene sample was found to be thermodynamically stable up to temperatures around 700oC.
Cite this paper
S. Watcharinyanon, L. I. Johansson, C. Xia, J. Ingo Flege, A. Meyer, J. Falta and C. Virojanadara, "Ytterbium Intercalation of Epitaxial Graphene Grown on Si-Face SiC," Graphene, Vol. 2 No. 2, 2013, pp. 66-73. doi: 10.4236/graphene.2013.22010.
S. Watcharinyanon, L. I. Johansson, C. Xia, J. Ingo Flege, A. Meyer, J. Falta and C. Virojanadara, "Ytterbium Intercalation of Epitaxial Graphene Grown on Si-Face SiC," Graphene, Vol. 2 No. 2, 2013, pp. 66-73. doi: 10.4236/graphene.2013.22010.
References
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[1] C. Virojanadara, A. A. Zakharov, R. Yakimova and L. I. Johansson, “Buffer Layer Free Large Area Bi-Layer Graphene on SiC(0001),” Surface Science, Vol. 604, 2010, pp. L4-L7. [2] C. Riedl, C. Coletti, T. Iwasaki, A. A. Zakharov and U. Starke, “Quasi-Free-Standing Epitaxial Graphene on SiC Obtained by Hydrogen Intercalation,” Physical Review Letters, Vol. 103, No. 24, 2009, Article ID: 246804. doi:10.1016/j.susc.2009.11.011 [3] S. Watcharinyanon, C. Virojanadara, J. R. Osiecki, A. A. Zakharov, R. Yakimova, R. I. G. Uhrberg and L. I. Johansson, “Hydrogen Intercalation of Graphene Grown on 6H- SiC(0001),” Surface Science, Vol. 605, No. 17-18, 2011, pp. 1662-1668. doi:10.1016/j.susc.2010.12.018 [4] K. V. Emtsev, F. Speck, T. Seyller, L. Ley and J. D. Riley, “Interaction, Growth, and Ordering of Epitaxial Graphene on SiC(0001) Surfaces: A Comparative Photoelectron Spectroscopy Study,” Physical Review B, Vol. 77, No. 15, 2008, Article ID: 155303. doi:10.1103/PhysRevB.77.155303 [5] F. Speck, J. Jobst, F. Fromm, M. Ostler, D. Waldmann, M. Hundhausen, H. B. Weber and T. Seyller, “The Quasi- Free-Standing Nature of Graphene on H-Saturated SiC (0001),” Applied Physics Letters, Vol. 99, No. 12, 2011, Article ID: 122106. doi:10.1063/1.3643034 [6] C. Virojanadara, S. Watcharinyanon, A. A. Zakharov and L. I. Johansson, “Epitaxial Graphene on 6H-SiC and Li Intercaltion,” Physical Review B, Vol. 82, No. 20, 2010, Article ID: 205402. doi:10.1103/PhysRevB.85.205402 [7] C. Virojanadara, A. A. Zakharov, S. Watcharinyanon, R. Yakimova and L. I. Johansson, “A LEEM and XPEEM Study of Li Intercalated into Graphene on SiC(0001),” New Journal of Physics, Vol. 12, 2010, Article ID: 125015. [8] S. Watcharinyanon, L. I. Johansson, C. Xia and C. Virojanadara, “Changes in Structural and Electronic Properties of Graphene Grown on 6H-SiC(0001) Induced by Na Deposition,” Journal of Applied Physics, Vol. 111, No. 8, 2012, Article ID: 083711. doi:10.1063/1.4704396 [9] A. Sandin, T. Jayasekera, J. E. Rowe, K. W. Kim, M. B. Nardelli and D. B. Dougherty, “Multiple Coexisting Intercalation Structures of Sodium in Epitaxial Graphene-SiC Interfaces,” Physical Review B, Vol. 85, No. 12, 2012, Article ID: 125410. doi:10.1103/PhysRevB.85.125410 [10] I. Gierz, T. Suzuki, R. T. Weitz, D. S. Lee, B. Krauss, C. Riedl, U. Starke, H. H?chst, J. H. Smet, C. R. Ast and K. Kern, “Electronic Decoupling of an Epitaxial Ggraphene Monolayer by Gold Intercalation,” Physical Review B, Vol. 81, No. 23, 2010, Article ID: 235408. doi:10.1103/PhysRevB.81.235408 [11] C. Xia, S. Watcharinyanon, A. A. Zakharov, R. Yakimova, L. Hultman, L. I. Johansson and C. Virojanadara, “Detailed Studies of Si Intercalation/Deintercalation of Graphene on 6H-SiC(0001),” Physical Review B, Vol. 85, No. 4, 2012, Article ID: 045418. doi:10.1103/PhysRevB.85.045418 [12] K. V. Emtsev, A. A. Zakharov, C. Coletti, S. Forti and U. Starke, “Ambipolar Doping in Quasifree Epitaxial Graphene on SiC(0001) Controlled by Ge Intercalation,” Physical Review B, Vol. 84, No. 12, 2011, Article ID: 125423. doi:10.1103/PhysRevB.84.125423 [13] A. L. Walter, K.-J. Jeon, A. Bostwick, F. Speck, M. Ostler, T. Seyller, L. Moreschini, Y. S. Kim, Y. J. Chang, K. Horn and E. Rotenberg, “Highly p-Doped Epitaxial Graphene Obtained by Fluorine Intercalation,” Applied Physics Letters, Vol. 98, No. 18, 2011, Article ID: 184102. doi:10.1063/1.3586256 [14] L. Meng, R. Wu, H. Zhou, G. Li, Y. Zhang, L. Li, Y. Wang and H.-J. Gao, “Silicon Intercalation at the Inter face of Graphene and Ir(111),” Applied Physics Letters, Vol. 100, No. 8, 2012, Article ID: 083101. doi:10.1063/1.3687688 [15] J. Sanchez-Barriga, A. Varykhalov, M. R. Scholz, O. Rader, D. Marchenko, A. Rybkin, A. M. Shikin and E. Vescovo, “Chemical Vapour Deposition of Graphene on Ni (111) and Co(0001) and Intercalation with Au to Study Dirac-Cone Formation and Rashba Splitting,” Diamond and Related Materials, Vol. 19, 2010, pp. 734-741. [16] S. Watcharinyanon, C. Virojanadara and L. I. Johansson, “Rb and Cs Deposition on Epitaxial Graphene Grown on 6H-SiC(0001),” Surface Science, Vol. 605, No. 21-22, 2011, pp. 1918-1922. doi:10.1016/j.susc.2011.07.007 [17] A. L. Walter, A. Bostwick, K.-J. Jeon, F. Speck, M. Ostler, T. Seyller, L. Moreschini, Y. J. Chang, M. Polini, R. Asgari, A. H. MacDonald, K. Horn and E. Rotenberg, “Effective Screening and the Plasmaron Bands in Graphene,” Physical Review B, Vol. 84, No. 8, 2011, Article ID: 085410.
doi:10.1103/PhysRevB.84.085410 [18] Private Communication with E. Rotenberg, 2011. [19] T. Loftus, J. R. Bochinski and T. W. Mossberg, “Magnetic Trapping of Ytterbium and the Alkaline-Earth Metals,” Physical Review A, Vol. 66, No. 1, 2002, Article ID: 013411.
doi:10.1103/PhysRevA.66.013411 [20] S. L. Molodtsov, C. Laubschat, M. Richter, T. Gantz and A. M. Shikin, “Electronic Struture of Eu and Yb Graphite Intercaltion Compounds,” Physical Review B, Vol. 53, No. 24, 1996, pp. 16621-16629. doi:10.1103/PhysRevB.53.16621 [21] A. M. Shikin, M. V. Poigin, Y. S. Dedkov, S. L. Molod- tsov and V. K. Adamchuk, “Formation of Intercalate-Like System of Graphite-Yttibium Monolayers on the Ni(111) Surface,” Physics of the Solid State, Vol. 42, No. 6, 2000, pp. 1170-1175. doi:10.1134/1.1131335 [22] T. E. Weller, M. Ellerby, S. Saxena, R. P. Smith and N. T. Skipper, “Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca,” Nature Physics, Vol. 1, No. 1, 2005, pp. 39-41. doi:10.1038/nphys0010 [23] C. Virojanadara, M. Syv?j?rvi, R. Yakimova, L. I. Johansson, A. A. Zakharov and T. Balasubramanian, “Homogeneous Large-Area Graphene Layer Growth on 6H- SiC(0001),” Physical Review B, Vol. 78, No. 24, 2008, Article ID: 245403. doi:10.1103/PhysRevB.78.245403 [24] T. Ohta, F. E. Gabaly, A. Bostwick, J. L. McChesney, K. V. Emtsev, A. K. Schmid, T. Seyller, K. Horn and E. Rotenberg, “Morphology of Graphene Thin Film Growth on SiC(0001),” New Journal of Physics, Vol. 10, No. 2, 2008, Article ID: 023034. doi:10.1088/1367-2630/10/2/023034 [25] L. N. Srivastava, G. He, R. M. Feenstra and P. J. Fisher, “Comparing of Graphene Formation on C-Face and Si- Face SiC(0001) Surfaces,” Physical Review B, Vol. 82, No. 23, 2010, Article ID: 235406. doi:10.1103/PhysRevB.82.235406 [26] C. Virojanadara, R. Yakimova, A. A. Zakharov and L. I. Johansson, “Large Homogeneous Mono/Bi-layer Graphene on 6H-SiC(0001) and Buffer Layer Elimination,” Journal of Physics D, Vol. 43, No. 37, 2010, Article ID: 374010. doi:10.1088/0022-3727/43/37/374010 [27] T. Ohta, A. Bostwick, J. L. McChesney, T. Seyller, K. Horn and E. Rotenberg, “Interlayer Interaction and Electronic Screening in Multilayer Graphene Investigated with Angle-Resolved Photoemission Spectroscopy,” Physical Review Letters, Vol. 98, No. 20, 2007, Article ID: 206802. doi:10.1103/PhysRevLett.98.206802 [28] P. H. Mahowald, D. J. Friedman, G. P. Carey, K. A. Bertness and J. J. Yeah, “Computer Program for Photoemission Data Analysis and Display,” Journal of Vacuum Science & Technology A, Vol. 5, No. 5, 1987, pp. 2982- 2985. doi:10.1116/1.574244 [29] R. Hofmann, W. A. Henle and F. P. Netzer, “Electronic Structure of Epitaxial Yb Silicide,” Physical Review B, Vol. 46, No. 7, 1992, pp. 3857-3864. doi:10.1103/PhysRevB.46.3857 [30] E.-J. Cho, J.-S. Chung, S.-J. Oh, S. Suga, M. Taniguchi, A. Kakizaki, A. Fujimori, H. Kato, T. Miyahara, T. Suzuki and T. Kasuya, “Surface Core-Level Shifts and Electronic Structures of Yb Compounds Studied with Use of Photoemission Spectrocopy,” Physical Review B, Vol. 47, No. 7, 1993, pp. 3933-3943. doi:10.1103/PhysRevB.47.3933 [31] F. Gerken, A. S. Flodstrom, J. Barth, L. I. Johansson and C. Kunz, “Surface Core Level Shifts of the Lanthanide Metal Ce58-Lu71: A Comprehensive Experiment Study,” Physica Scripta, Vol. 32, No. 1, 1985, pp. 43-57. doi:10.1088/0031-8949/32/1/006 [32] C. Wigren, J. N. Andersen, R. Nyholm and U. O. Karlsson, “Growth and Epitaxy of Yb Silicides on Si(111),” Journal of Vacuum Science & Technology A, Vol. 9, 1991, pp. 1942-1945. doi:10.1116/1.577549 [33] J. Ristein, S. Mammadov and T. Seyller, “Origin of Doping in Quasi-Free-Standing Graphene on SiC,” Physical Review Letters, Vol. 108, No. 24, 2012, Article ID: 246104.
doi:10.1103/PhysRevLett.108.246104 [34] A. Bostwick, T. Ohta, T. Seyller, K. Horn and E. Rotenberg, “Quasiparticle Dynamics in Graphene,” Nature Physics, Vol. 3, No. 1, 2007, pp. 36-40. doi:10.1038/nphys477 [35] M. S. Altman, W. F. Chung and C. H. Liu, “LEEM Phase Contrast,” Surface Review and Letters, Vol. 5, No. 6, 1998, pp. 1129-1141. doi:10.1142/S0218625X98001468 [36] J. I. Flege, A. Meyer, J. Falta and E. E. Krasovskii, “Self-Limited Oxide Formation in Ni(111) Oxidation,” Physical Review B, Vol. 84, No. 11, 2012, Article ID: 115441. doi:10.1103/PhysRevB.84.115441