Modeling of graphene-based NEMS

The possibility of designing nanoelectromechanical systems (NEMS) based on relative motion or vibrations of graphene layers is analyzed. Ab initio and empirical calculations of the potential relief of interlayer interaction energy in bilayer graphene are performed. A new potential based on the density functional theory calculations with the dispersion correction is developed to reliably reproduce the potential relief of interlayer interaction energy in bilayer graphene. Telescopic oscillations and small relative vibrations of graphene layers are investigated using molecular dynamics simulations. It is shown that these vibrations are characterized with small Q-factor values. The perspectives of nanoelectromechanical systems based on relative motion or vibrations of graphene layers are discussed.Comment: 19 pages, 4 figure

First-principles Investigation Of The Wchf O2 Interface Properties

The thermodynamic and electronic properties of tungsten carbide surfaces and interfaces with monoclinic hafnia (WCm-Hf O2) are investigated through first-principles calculations. We show that oxidation of the WC surface and of the WCm-Hf O2 interface is energetically favorable. An oxygen monolayer on the W-terminated WC(0001) surface gives rise to a larger vacuum work function than that for the C-terminated WC(0001) surface, while the opposite result is obtained for the WC(0001) effective work function on hafnia: a carbon intermediate layer results in larger work function than an oxygen intermediate layer. This result is explained by the atomic structure of the intermediate layers neighboring the interface which differ if the interface is O or C rich. © 2006 American Institute of Physics.998The International Technology Roadmap for Semiconductors., , http://public.itrs.orgWilk, G.D., Wallace, R.M., Anthony, J.M., (2000) J. Appl. Phys., 87, p. 484Hobbs, C.C., (2004) IEEE Trans. Electron Devices, 51, pp. 971/978Yeo, Y.-C., King, T.-J., Hu, C., (2002) J. Appl. Phys., 92, p. 7266Haglung, J., Guillermet, A.F., Grimvall, G., Korling, M., (1993) Phys. Rev. B, 48, p. 11685Kobayashi, K., (2001) Surf. Sci., 493, p. 665Liu, A.Y., Wentzcovitch, R.M., Cohen, M.L., (1988) Phys. Rev. B, 38, p. 9483Wang, S.J., Tsai, H.Y., Sun, S.C., (2001) Thin Solid Films, 394, p. 180Sun, Y.-M., (2001) Thin Solid Films, 397, p. 109Romanus, H., Cimalla, V., Schaefer, J.A., Spieb, L., Ecke, G., Pezoldt, J., (2000) Thin Solid Films, 359, p. 146Hogberg, H., Tagtstrom, P., Lu, J., Jansson, U., (1996) Thin Solid Films, 272, p. 116Hakansson, K.L., Johansson, H.I.P., Johansson, L.I., (1994) Phys. Rev. B, 49, p. 2035Brillo, J., Hammoudeh, A., Kuhlenbeck, H., Panagiotides, N., Schwegmann, S., Over, H., Freund, H.-J., (1998) J. Electron Spectrosc. Relat. Phenom., 96, p. 53Gothelid, M., Janin, E., (1999) J. Phys.: Condens. Matter, 11, p. 773Siegel, D.J., Hector Jr., L.G., Adams, J.B., (2002) Surf. Sci., 498, p. 321Mattheiss, L.F., Hamann, D.R., (1984) Phys. Rev. B, 30, p. 1731Brillo, J., Kuhlenbeck, H., Freund, H.-J., (1998) Surf. Sci., 409, p. 199Ceperley, D.M., Alder, B.J., (1980) Phys. Rev. Lett., 45, p. 566. , 0031-9007 10.1103/PhysRevLett.45.566Perdew, J.P., Zunger, A., (1981) Phys. Rev. B, 23, p. 5048Perdew, J.P., Wang, Y., (1992) Phys. Rev. B, 46, p. 6671Hohenberg, P., Kohn, W., (1964) Phys. Rev., 136, p. 864. , 0096-8269 10.1103/PhysRev.136.B864Kohn, W., Sham, L.J., (1965) Phys. Rev., 140, p. 1133Kresse, G., Furthmuller, J., (1996) Phys. Rev. B, 54, p. 11169Kresse, G., Hafner, J., (1994) J. Phys.: Condens. Matter, 6, p. 8245Edwards, J.W., Speiser, R., Johnston, H.L., (1951) J. Appl. Phys., 22, p. 424Weast, R.C., (1983) CRC Handbook of Chemistry and Physics, , 67th ed., (CRC, Boca RatonRuh, R., Corfield, P.W.R., (1970) J. Am. Ceram. Soc., 53, p. 126Foster, A.S., Lopez Gejo, F., Shluger, A.L., Nieminen, R.M., (2002) Phys. Rev. B, 65, p. 174117Batyrev, I., Alavi, A., Finnis, M.W., (2000) Faraday Discuss., 114, p. 33Michaelson, H., (1977) J. Appl. Phys., 48, p. 4729Demkov, A.A., Lui, R., Zhang, X., Loechelt, H., (2000) J. Vac. Sci. Technol. B, 18, p. 2338Van De Walle, C.G., Martin, R.M., (1989) Phys. Rev. B, 39, p. 1871(1978) Thermodynamic Properties of Individual Substances, , edited by V. P.Glushko (Nauka, MoscowPuthenkovilakam, R., Chang, J.P., (2004) Appl. Phys. Lett., 84, p. 1353Cook Jr., T.E., Fulton, C.C., Mecouch, W.J., Davis, R.F., Lucovsky, G., Nemanich, R.J., (2003) J. Appl. Phys., 94, p. 7155Schaeffer, J., Knizhnik, A., Iskandarova, I., Bagatur'yants, A., Potapkin, B., Fonseca, L.R.C., (2005) J. Appl. Phys., 97, p. 64911Králik, B., Chang, E.K., Louie, S.G., (1998) Phys. Rev. B, 57, p. 702

Segregation Trends Of The Metal Alloys Mo-re And Mo-pt On Hfo 2: A First-principles Study

Using first-principles calculations, we compared the segregation trends at the surface of metal alloys with those at an interface with HfO 2. The choice of this oxide was motivated by its significance as a potential replacement for SiO 2 in advanced transistors. We considered Mo-Re and Mo-Pt alloys as typical examples of disordered and ordered alloys, respectively. The segregation to the surface/interface was analyzed in terms of metal and oxygen adsorption energies. It is shown that chemical bonding at the metal/oxide interface strongly influences segregation both in Mo-Re and Mo-Pt alloys. In particular, bonding with oxygen atoms at the oxide/Mo-Re alloy interface depletes the Re content of the interfacial layer. In the case of Mo-Pt on HfO 2 an oxygen-rich interface promotes the formation of one monolayer (but not two monolayers) of Mo separating PtMo x from HfO 2, while a stoichiometric interface favors an abrupt PtMo xHfO 2 interface. This study also shows that the presence of Mo in the alloy stabilizes Pt which can potentially decrease the tendency of Pt to diffuse into the oxide matrix. The individual constituents of these intermetallic compounds exhibit high vacuum work functions, and therefore these alloys are also likely to have sufficiently high work functions to be considered as promising candidates for p-type gate electrodes in future generations of transistors. © 2006 American Institute of Physics.1001Bozzolo, G., Ferrante, J., Noebe, R.D., Good, B., Honecy, F.S., Abel, P., (1999) Comput. Mater. Sci., 15, p. 169Treglia, G., Legrand, B., Ducastelle, F., Saul, A., Gallis, C., Meunier, I., Mottet, C., Senhaji, A., (1999) Comput. Mater. Sci., 15, p. 196Heinz, K., Hammer, L., (1999) J. Phys.: Condens. Matter, 11, p. 8377Ruban, A.V., Skriver, H.L., Norskov, J.K., (1999) Phys. Rev. B, 59, p. 15990Modrak, P., (1996) Surf. Sci. Lett., 349, pp. L128Christoffersen, E., Stoltze, P., Norskov, J.K., (2002) Surf. Sci., 505, p. 200Stefanov, P., (1997) Appl. Surf. Sci., 108, p. 477The International Technology Roadmap for Semiconductors, , http://public.itrs.orgHobbs, C.C., (2004) IEEE Trans. Electron Devices, 51, p. 971Hobbs, C.C., (2004) IEEE Trans. Electron Devices, 51, p. 978Yeo, Y.-C., King, T.-J., Hu, C., (2002) J. Appl. Phys., 92, p. 7266Knizhnik, A.A., Iskandarova, I.M., Bagatur'yants, A.A., Fonseca, L.R.C., (2005) J. Appl. Phys., 97, p. 64911Davis, H.L., Zehner, D.M., Dotsch, B., Wimmer, A., Muller, K., (1991) Bull. Am. Phys. Soc., 36, p. 705Doll, R., Kottcke, M., Heinz, K., Hammer, L., Muller, K., Zehner, D.M., (1994) Surf. Sci., 307-309, p. 434Kottcke, M., Dotsch, B., Hammer, L., Heinz, K., Muller, K., Zehner, D.M., (1997) Surf. Sci., 376, p. 319Hammer, L., Kottcke, M., Taubmann, M., Meyer, S., Rath, C., Heinz, K., (1999) Surf. Sci., 431, p. 220Hultgren, R., Desai, P.D., Hawkins, D.T., Gleiser, M., Kelley, K.K., (1973) Selected Values of Thermodynamic Properties of Binary Alloys, , American Society for Metals, Metals Park, OH(1983) Smithells Metal Reference Book, 6th Ed., pp. 11-358. , edited by E. A. Brandes Butterworths, LondonOuannasser, S., Dreysse, H., (2003) Surf. Sci., 523, p. 151Deng, H., Hu, W., Shu, X., Zhang, B., (2003) Surf. Sci., 543, p. 95Elliott, R.P., (1965) Constitution of Binary Alloys, , McGraw Hill, New YorkGuo, Q., Kleppa, O.J., (2001) J. Alloys Compd., 321, p. 169Basset, D.W., (1995) Surf. Sci., 325, p. 121Eckschlager, A., Athenstaedt, W., Leisch, M., Fresenius (1998) J. Anal. Chem., 361, p. 672Ceperley, M., Alder, B.J., (1980) Phys. Rev. Lett., 45, p. 566Perdew, J.P., Zunger, A., (1981) Phys. Rev. B, 23, p. 5048Hohenberg, P., Kohn, W., (1964) Phys. Rev., 136, pp. B864Kohn, W., Sham, L.J., (1965) Phys. Rev., 140, pp. A1133Kresse, G., Furthmuller, J., (1996) Phys. Rev. B, 54, p. 11169Kresse, G., Hafner, J., (1994) J. Phys.: Condens. Matter, 6, p. 8245http://www.webelements.comRuh, R., Corfield, P.W.R., (1970) J. Am. Ceram. Soc., 53, p. 126Blöchl, P.E., (1994) Phys. Rev. B, 50, p. 17953Feibelman, P.J., (1995) Phys. Rev. B, 52, p. 16845Vitos, L., Ruban, A.V., Skriver, H.L., Kollar, J., (1998) Surf. Sci., 411, p. 186Michaelson, H., (1977) J. Appl. Phys., 48, p. 4729Perdew, J.P., Burke, K., Ernzerhof, M., (1996) Phys. Rev. Lett., 77, p. 3865Kresse, G., Joibert, D., (1999) Phys. Rev. B, 59, p. 175