LOW-ENERGY ELECTRON-DIFFRACTION INTENSITY ANALYSIS OF THE ATOMIC GEOMETRY OF P(1X1) MONOLAYERS OF BISMUTH ON GAAS(110)

The elastic low-energy electron diffraction intensities of 18 diffracted beams associated with electrons normally incident on GaAs(110)-p(1X 1)—Bi(1 ML) (monolayer) have been measured at 130 K. Analysis of these beams using a multiple scattering methodology previously applied to GaAs(llO) and GaAs(110)-p(1 × 1)-Sb(1 ML) yields a best-fit structure characterized by a bond-length-conserving top layer rotation of chains of Bi atoms by a tilt angle of ω1= 3° ± 2° and a counter rotation (Ga displaced outward toward the Bi overlayer) in the underlying GaAs(110) layer of ω2— — 3° + 2°. A small contraction of the top-layer spacing is possible but is not mandated by the analysis. Only geometries analogous to that of GaAs(110)-P(1 × 1)-Sb(1 ML) were included in the structural search. © 1990, American Vacuum Society. All rights reserved.