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calculated binding energies of the quantum well states to the observed values. The calculated binding energies of the quantum well state from the fit are shown as open circles connected by lines in Fig. 2, and the quantum number n for each branch is indicated. The results agree well with the experimental values shown as crosses. The experimental value for the quantum well state at N = 11 is not included in the figure because the peak is too close to the Fermi level for a precise determination of its position. The confinement edge at 0.5 eV is indicated by a horizontal dashed line in Fig. 2. In agreement with experimental observations, no quantum well states exist, or only weak resonances are observed, for even N = 4, 6, 8, and 10, while intense quantum-well states are observed for odd N = 5, 7, and 9. This difference between even- and odd-N configurations is just a consequence of the way that the quantum well states evolve as a function of thickness as seen in Fig. 2. This evolution is largely determined by the band structure [3, 5, 8, 9]. It happens that one half of the Fermi wave length in Pb is approximately two atomic layers, and a simple analysis based on Eq. (1) shows that a new quantum well state drops below the Fermi level for a film thickness increment of about two atomic layers [3, 5]. The corresponding changes in the occupied density of states should give rise to an oscillation period of about two atomic layers for essentially all physical properties of the films. Also in agreement with our experimental observation is that no quantum well states are predicted for N = 1-3. Numerous groups have experimented with Pb growth on Si [8-13], but none has achieved atomic uniformity. Prior to this experiment, we had performed extensive experimentation with direct deposition on the (7x7) reconstructed Si(111) at various temperatures, but the resulting films were inevitably rough. In the present experiment, the atomic-layer uniformity is achieved by first preparing either the or 3 3 reconstructions [12, 14, 15]. Our experiment shows that deposition of Pb on the phase, the phase, or any intermediate phases at a low temperature (100 K) leads to atomically uniform films. The final results are the same for the same total amounts of Pb deposition including the initial Pb coverages. The determination of film thicknesses is described in detail in [1]. The stability of the films has been measured, and some interesting features were observed, including the bilayer oscillation predicted by Wei et al. [17]. Why does Pb pretreatment promote uniform film formation, while direct deposition on Si(111)-(7x7) does not work? A possible explanation is that the (7x7) surface, with its complicated reconstruction involving adatoms, dimers, corner holes, and partial stacking fault, is not smooth on the atomic scale. These structural features can pin the Pb growth locally at low temperatures, resulting in small crystallites that are structurally incoherent. Increasing the substrate temperature to promote long-range diffusion and structural coherence leads to formation of islands instead of smooth films due to electronic effects [10, 16]. Pretreatment of Si by Pb leads to a smooth bulk-terminated Si substrate with a well ordered Pb overlayer. This can be a good template for smooth growth upon further deposition at low temperatures. Our results illustrate an important issue in film growth – the initial surface structure can be a deciding factor for the morphological development of films. As shown in this study, proper conditioning of the starting surface allows us to make uniform films on Si, a result of potential interest and importance for nano and quantum electronics. This work is supported by the U.S. National Science Foundation (grant DMR-02-03003). We acknowledge the Petroleum Research Fund, administered by the American Chemical Society, and the U.S. Department of Energy, Division of Materials Sciences (grant DEFG02- 91ER45439), for partial support of the synchrotron beamline operation and the central facilities
of the Frederick Seitz Materials Research Laboratory. The Synchrotron Radiation Center of the University of Wisconsin-Madison is supported by the U.S. National Science Foundation (grant DMR-00-84402). References: [1] M. Upton, T. Miller, and T.-C Chiang, Phys. Rev. B, in press. [2] J. J. Paggel, T. Miller, and T.-C. Chiang, Phys. Rev. Lett. 81, 5632 (1998); Science 283, 1709 (1999). [3] T.-C. Chiang, Surf. Sci. Rep. 39, 181 (2000), and references therein. [4] A Schottky barrier height of 0.93 eV was reported by D. R. Heslinga, H. H. Weitering, D. P. van der Werf, T. M. Klapwijk, and T. Hibma, Phys. Rev. Lett. 64, 1589 (1990). In a more recent study by R. F. Schmitsdorf and W. Mönch, Eur. Phys. J. B 7, 457 (1999), a value of 0.72 0.02 eV was reported. [5] C. M. Wei and M. Y. Chou, Phys. Rev. B 66, 233408 (2002). [6] D.-A. Luh, T. Miller, J. J. Paggel, and T.-C. Chiang, Phys. Rev. Lett. 88, 256802 (2002). [7] N. V. Smith, Phys. Rev. B 32, 3549 (1985). [8] A. Mans, J. H. Dil, A. R. H. F. Etterma, and H. H. Weitering, Phys. Rev. B 66, 195410 (2002). [9] M. Jalochowski, H. Knoppe, G. Lilienkamp, and E. Bauer, Phys. Rev. B 46, 4693 (1992); M. Jalochowski, M. Hoffmann, and E. Bauer, Phys. Rev. B 51, 7231 (1995); Th. Schmidt and E. Bauer, Surf. Sci. 480, 137 (2001). [10] M. Hupalo and M. C. Tringides, Phys. Rev. B 65, 115406 (2002). M. Hupalo, V. Yeh, L. Berbil-Bautista, S. Kremmer, E. Abram, and M. C. Tringides, Phys. Rev. B 64, 155307 (2001). [11] W. B. Su, S. H. Chang, W. B. Jian, C. S. Chang, L. J. Chen, and T. T. Tsong, Phys. Rev. Lett. 86, 5116 (2001). [12] I.-S. Hwang, R. E. Martinez, C. Liu, and J. A. Golovchenko, Surf. Sci. 323, 241 (1995). [13] I. B. Altfeder, K. A. Matveev, and D. M. Chen, Phys. Rev. Lett. 78, 2815 (1997). [14] J. A. Carlisle, T. Miller, and T.-C. Chiang, Phys. Rev. B 45, 3400 (1992). [15] P. J. Estrup and J. Morrison, Surf. Sci. 2, 465 (1964). [16] Hawoong Hong, C. M. Wei, M. Y. Chou, Z. Wu, L. Basile, H. Chen, M. Holt, and T.-C. Chiang, Phys. Rev. Lett. 90, 076104 (2003). [17] C. M. Wei, and M. Y. Chou, Phys. Rev. B 66, 233408 (2002).
Page 2 and 3: Welcome to the 36 th SRC Users’ M
Page 4 and 5: 12:20 - 1:10 Lunch 1:10 -1:45 Poste
Page 6 and 7: Administration Executive Director D
Page 8 and 9: STATUS OF THE SRC BEAMLINES AND INS
Page 10 and 11: ACCELERATOR DEVELOPMENTS Ken Jacobs
Page 12 and 13: HIGH ENERGY RESEARCH POSSIBILITIES
Page 14 and 15: ATOMICALLY UNIFORM THIN FILMS ON SI
Page 18 and 19: MANY-ELECTRON EFFECTS ON THE XE 5S
Page 20 and 21: PHOTOELECTRON SPECTROMETRY OF ATOMI
Page 22 and 23: PHOTOEMISSION STUDY OF USb AND UTe
Page 24 and 25: CANADIAN SYNCHROTRON RADIATION FACI
Page 26 and 27: SELF-ASSEMBLY OF BLOCK COPOLYMERS O
Page 28 and 29: A B S T R A C T S
Page 30 and 31: Photoemission spectra, a.u. -0.3 -0
Page 32 and 33: THE INITIAL AND FINAL STATE BANDS I
Page 34 and 35: TRANSITION LAYERS AT BURIED FERROMA
Page 36 and 37: LOW-DIMENSIONAL ELECTRONS AT SILICO
Page 38 and 39: SUBCELLULAR DISTRIBUTION OF MOTEXAF
Page 40 and 41: LINEAR POLARIZATION MEASUREMENTS OF
Page 42 and 43: Fig.1: Photoemission spectra of opt
Page 44 and 45: The sample manipulator has a cool d
Page 46 and 47: Cr and Fe but for these U systems t
Page 48 and 49: [4] G. -H. Gweon, J. W. Allen, and
Page 50 and 51: References [1] S. Cho, Y. Kim, A. D
Page 52 and 53: [3] D. L. Mills, Physical Review B
Page 54 and 55: CHARACTERIZATION OF SULPHATE INTERA
Page 56 and 57: in the data acquisition chamber. Th
Page 58 and 59: spatially resolved chemistry of the
Page 60 and 61: THE RELATIONSHIP BETWEEN PHOSPHATE
Page 62 and 63: PHOTOEMISSION STUDIES OF QUANTUM WE
Page 64 and 65: Ag surface state such that it moves
Page 66 and 67:
HIGH-RESOLUTION STUDY OF THE LITHIU
Page 68 and 69:
RELATIVE PARTIAL CROSS SECTIONS AND
Page 70 and 71:
Christian Ast Max-Planck Institute
Page 72 and 73:
David L. Huber Physical Sciences La
Page 74 and 75:
Tom Miller University of Illinois a
Page 76 and 77:
Eric Wiedemann University of Wiscon
Page 78 and 79:
Pete Hagen Phone: (608) 877-2154 Em
Page 80:
NOTES
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