Investigation of Symmetry Properties of Surfaces by Means of Backscattered Electrons

Abstract

Secondary-electron imaging is presented as a practical method which allows investigation of the near-surface structure in real time. It is based on the observation that electrons backscattered from surfaces in the keV range show a strong enhancement of intensity along directions defined by atomic rows. The spatial imaging of such electrons reveals the symmetry of near-surface regions in real space. Three-dimensional views of the solid are readily obtained, which makes this method ideally suited for the study of unknown structures and any material system where there is a change of symmetry.

Structure of epitaxial Gd2O3 films and their registry on GaAs(100) substrates

“…3 Here, we report a study on the structure and alignment of such Gd 2 O 3 films on GaAs(100) using secondary electron imaging (SEI). 4 In agreement with previous x-ray diffraction data, 3 we have determined the structure of the dielectric layer and its registry with the GaAs substrate and obtained atomistic insight into the unusual super-cell epitaxy. …”

Structural modifications upon deposition of Fe on the icosahedral quasicrystal Al–Pd–Mn

“…1b the corresponding SEI pattern displaying the 5f symmetry of the surface is depicted. Several Kikuchi bands [12] as well as twofold (2f)-and threefold (3f)-symmetry axes are observable. These patterns are obtained using the same experimental geometry except for the electron energy.…”

“…In this work, we report on the deposition of Fe on the fivefold (5f)-symmetry surface of the icosahedral QC Al 70 Pd 20 Mn 10 (Al-Pd-Mn) kept at $340 K using low-energy electron diffraction (LEED) and secondary-electron imaging (SEI) [12]. The chemical composition was monitored by Auger electron spectroscopy (AES), and magneto-optical Kerr effect (MOKE) measurements were performed in order to detect magnetic ordering at the sample surface.…”

Structure of Gd2O3 films epitaxially grown on GaAs(100) and GaN(0001) surfaces

“…The information in SEI originates from a volume fraction of the specimen given by the spot size of the primary electron beam on the surface (0.2 mm) and the mean free path of the electrons (¾1.8 nm). 4,5 X-ray photoelectron spectroscopy (XPS) was performed to obtain information on the total electronic density of occupied states and to measure the core-level E B of the atoms present near the surface. Excitation was done with an unmonochromatized Al K˛radiation source.…”

“…In contrast to thin Gd 2 O 3 films on GaAs, these films remain stable during annealing and are resistant to exposure of ion beams. Using the technique of secondary electron imaging (SEI), 4 we find that there is a high degree of rotational alignment of crystallographic features at the Gd 2 O 3 /GaN interface, even though there is a lattice mismatch between the film and the substrate.…”