OVERLAYER GROWTH AND ELECTRONIC PROPERTIES OF THE BI/GASB(11O) INTERFACE

Luca Gavioli, Maria Grazia Betti, Carlo Mariani

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9 Citations (Scopus)

Abstract

The overlayer growth and electronic properties of the Bi/GaSb(110) interface and of the two-dimensional ordered (1×1)- and (1×2)-Bi layers have been investigated by complementary spectroscopic techniques (high-resolution electron-energy-loss, photoemission, and Auger spectroscopy). Bismuth forms an epitaxial monolayer, followed by island formation (Stranski-Krastanov growth mode) covering an average surface area of 40% at a nominal coverage of 4 ML. The (1×2)-symmetry stable structural phase, obtained after annealing at ~220 °C, corresponds to an average nominal Bi coverage of about 0.7 ML, suggesting an atomic geometry different from the epitaxial-continued layer structure. The disposal of Bi atoms in the (1×2) structure should build up an ``open'' layer, as the Ga-related surface exciton quenched in the (1×1) epitaxial monolayer is present in the (1×2) stable phase. The two symmetry phases are characterized by strong absorption features at 1 eV [(1×1)-Bi] and 0.54 eV [(1×2)-Bi], related to interband electronic transitions between Bi-induced electronic states. The major Bi-related occupied electronic levels, present in the valence band of the (1×1)- and (1×2)-Bi layer, have been detected by angle-integrated ultraviolet photoemission spectroscopy. Both the (1×1) and (1×2) phases show a metallic nature, with a low density of electronic states at the Fermi level. Schottky barrier heights of 0.20 and 0.14 eV are estimated for the epitaxial (1×1)- and (1×2)-symmetry stage, respectively, by analyzing the space-charge layer conditions through the study of the dopant-induced free-carrier plasmon in the GaSb substrate.
Original languageEnglish
Pages (from-to)16822-16831
Number of pages10
JournalPHYSICAL REVIEW. B, CONDENSED MATTER
Volume51
DOIs
Publication statusPublished - 1995

Keywords

  • ANGLE-RESOLVED PHOTOEMISSION
  • ATOMIC GEOMETRY
  • DEPENDENT SURFACE-STATES
  • ENERGY-LOSS SPECTROSCOPY
  • GAAS(110)
  • III-V COMPOUNDS
  • RAY STANDING-WAVE
  • SB OVERLAYERS
  • SEMICONDUCTOR SURFACES
  • SYNCHROTRON-RADIATION

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