Quantum-well states in ultrathin Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces

Article

关键词: BAND-STRUCTURE;    HYDROGEN-TERMINATION;    AG NANOFILMS;    THIN-FILM;    PHOTOEMISSION;    GROWTH;    OVERLAYERS;    INTERFACE;    ISLANDS;    AG(100);   

DOI  :  10.1103/PhysRevB.65.195410

来源: SCIE

【 摘 要 】

Ag(111) films were deposited at room temperature onto H-passivated Si(111)-(1x1) substrates, and subsequently annealed at 300 degreesC. An abrupt nonreactive Ag/Si interface is formed, and very uniform nonstrained Ag(111) films of 6-12 ML have been grown. Angle-resolved photoemission spectroscopy was used to study the valence band electronic properties of these films. Well-defined Ag sp quantum-well states (QWS's) have been observed at discrete energies between 0.5-2 eV below the Fermi level, and their dispersions have been measured along the (&UGamma;K) over bar, <(&UGamma;M(M'))over bar>, and GammaL symmetry directions. QWS's show a parabolic bidimensional dispersion, with in-plane effective mass of (0.38-0.50)m(o), along the (&UGamma;K) over bar and <(&UGamma;M(M'))over bar> directions, whereas no dispersion has been found along the GammaL direction, indicating the low-dimensional electronic character of these states. The binding energy dependence of the QWS as a function of the Ag film thickness has been analyzed in the framework of the phase accumulation model. A good agreement between experimental data and the above-mentioned model is obtained for the Ag/H/Si(111)-(1x1) system. Hydrogen at the interface not only enhances the Ag film uniformity, but also acts as a barrier modifying the phase change of the Ag-sp electron wave upon reflection at the Ag/Si interface.

【 授权许可】

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