The band alignment problem at the Si-high-k dielectric interface

ABSTRACTWe investigate the use of the complex band structure of high-k gate dielectrics to estimate their charge neutrality levels, and compute band offsets to Si. Results of these model calculations are then compared to those obtained with direct electronic structure methods and available experiment. It appears that charge neutrality levels thus obtained indeed provide a consistent picture. However, the uncertainty in the conduction band position inherent in the local density approximation may render the theory inadequate for the engineering support. Despite this limitation, linear re-scaling of the charge neutrality levels based on the experimental band gaps has shown excellent agreement with experimental data.</jats:p

Ab Initio Modeling Of Contact Structure Formation Of Carbon Nanotubes And Its Effect On Electron Transport

Carbon nanotube (CNT) devices are studied as a possible alternative to the current silicon based CMOS technology. The contacts between CNTs and metal electrodes in such devices exert great influence on the device performance. In this study, ab initio temperature accelerated dynamics are performed to study the contact formation between CNTs and Ti electrodes. Results indicate that CNTs undergo significant structural deformation, resulting in a significant decrease of the device conductance. This finding may explain the discrepancy between experimental and simulated results in molecular devices. However, more effects may need to be taken into account as we discuss for the example of the size effect of CNTs. Mater. Res. Soc. Symp. Proc. Vol. 1081 © 2008 Materials Research Society.1081113118Nitzan, A., Ratner, M.A., (2003) Science, 300, p. 1384Ghosh, A.W., Datta, S., (2002) J. Comput. Electron., 1, p. 515Wind, S.J., (2003) Journal of Vacuum Science & Technology B, 21 (6), pp. 2856-2859Javey, A., (2003) Nature, 424 (6949), pp. 654-657Ventra, M.D., Pantelides, S.T., Lang, N.D., (2000) Phys. Rev. Lett., 84, p. 979Reed, M.A., Proceedings of the Ieee, 1999, 87 (4), pp. 652-658Voter, A.F., Montalenti, F., Germann, T.C., (2002) Annual Review of Materials Research, 32, pp. 321-346Datta, S., (1995) Electronic Transport in Mesoscopic Systems, , Cambridge, MA: Cambridge University PressZhang, X., Fonseca, L., Demkov, A.A., (2002) Physica Status Solidi B-Basic Research, 233 (1), pp. 70-82Kresse, G., Hafner, J., (1993) Phys. Rev. B, 47, p. 558Kresse, G., Hafner, J., (1994) Phys. Rev. B, 49, p. 14251Blochl, P.E., (1994) Phys. Rev. B, 50, p. 17953Perdew, J.P., Wang, Y., (1992) Phys. Rev. B, 45, p. 13244Tibbetts, G.G., (1984) Journal of Crystal Growth, 66 (3), pp. 632-63

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

Grain boundary composition and conduction in HfO2: An ab initio study

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