Crystal Surface Symmetry from Zone-Axis Patterns in Reflection High-Energy-Electron Diffraction

1984 ◽  
Vol 53 (22) ◽  
pp. 2125-2128 ◽  
Author(s):  
M. D. Shannon ◽  
J. A. Eades ◽  
M. E. Meichle ◽  
P. S. Turner ◽  
B. F. Buxton
Keyword(s):  
Electron Diffraction ◽  
Crystal Surface ◽  
High Energy ◽  
Zone Axis ◽  
Energy Electron ◽  
High Energy Electron

A `three-beam' analysis of resonance scattering in reflection high-energy electron diffraction

1999 ◽  
Vol 55 (2) ◽  
pp. 197-203 ◽  
Author(s):  
G. R. Anstis
Keyword(s):  
Electron Diffraction ◽  
Crystal Surface ◽  
Incident Beam ◽  
Resonance Scattering ◽  
High Energy ◽  
Energy Electron ◽  
Quantitative Prediction ◽  
Perturbation Approach ◽  
High Energy Electron ◽  
Depth Of Penetration

Enhanced reflection of fast electrons from a crystal surface and a decrease in the depth of penetration of the primary beam occurs when diffraction conditions are such as to set up a wave travelling just beneath the crystal surface. This is the surface resonance condition for reflection high-energy electron diffraction (RHEED). Quantitative prediction of these effects can be achieved by assuming that only the primary and two diffracted beams are significant. Expressions for the coefficient of reflection and the depth of penetration in terms of a few Fourier coefficients of an effective potential are derived. These coefficients depend sensitively on incident-beam direction and are significantly different from the values for the bulk crystal. In particular, the mean potential experienced by the electrons in the resonance state is increased. It can be estimated using Bethe's perturbation approach. Predictions of the position, height and width of the peak in reflectivity resulting from resonance scattering from the (111) surface of platinum are in reasonable agreement with the values obtained from many-beam computations. The three-beam approach gives insight into resonance scattering using the standard formalism of diffraction theory.

The Origin of Resonance Phenomena in Reflection High-Energy Electron Diffraction

1995 ◽  
Vol 404 ◽  
Author(s):  
S. L. Dudarev ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Crystal Surface ◽  
Resonance Scattering ◽  
High Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
Theoretical Understanding ◽  
Molecular Beam Epitaxial ◽  
High Energy Electrons ◽  
Molecular Beam Epitaxial Growth

AbstractResonance scattering of high-energy electrons is responsible for the appearance of bright features observed in reflection high-energy electron diffraction (RHEED) patterns and has found numerous applications in reflection electron microscopy and in RHEED studies of dynamics of molecular beam epitaxial growth of semiconductor crystals. In this paper we report on recent developments in theoretical understanding of the processes leading to resonance reflection of high-energy electrons from a crystal surface.

STRUCTURAL ANALYSIS OF CRYSTAL SURFACES BY REFLECTION HIGH ENERGY ELECTRON DIFFRACTION

1997 ◽  
Vol 04 (03) ◽  
pp. 501-511 ◽  
Author(s):  
AYAHIKO ICHIMIYA ◽  
YUSUKE OHNO ◽  
YOSHIMI HORIO
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Forward Direction ◽  
High Energy ◽  
Zone Axis ◽  
Energy Electron ◽  
High Energy Electron ◽  
Structure Determinations ◽  
The One ◽  
Diffraction Condition

For surface structure determinations by reflection high energy electron diffraction (RHEED), intensity rocking curves are analyzed through RHEED dynamical calculations. Since fast electrons are scattered dominantly in the forward direction by atoms, dynamic diffraction mainly occurs in the forward direction. By the use of this feature, it is possible to choose a diffraction condition under which electrons are diffracted mainly by lattice planes parallel to the surface, when the incident direction is chosen at a certain azimuthal angle with respect to a crystal zone axis. This diffraction condition is called the one-beam condition. Under this condition, the RHEED intensity is a function of interlayer distances and atomic densities of the surface layers. Therefore the surface normal components of the atomic positions are determined by analysis of the one-beam rocking curve using a RHEED dynamical calculation. Then, using the result of the surface normal components of atomic positions, lateral positions of the surface atoms are determined from analysis of the rocking curves at many-beam conditions, where the direction of the incident beam is chosen along a certain crystal zone axis. An example of the surface structure determination of a Si(111) surface at high temperatures is reported. We discuss effects of terraces and antiphase domains of surfaces in structure determinations by RHEED.

Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces

1990 ◽  
Vol 48 (2) ◽  
pp. 396-397
Author(s):  
L. -M. Peng ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Kinematic Analysis ◽  
Incident Beam ◽  
High Energy ◽  
Energy Electron ◽  
Great Success ◽  
High Energy Electron ◽  
Kinematic Approximation ◽  
Reconstructed Surfaces

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

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