Reflection Electron Microscopy

1977 ◽

Vol 35 ◽

pp. 316-317

Author(s):

G. G. Hembree ◽

M. A. Otooni ◽

J. M. Cowley

Keyword(s):

Electron Microscopy ◽

Electron Diffraction ◽

Single Crystal ◽

Crystal Surface ◽

Crystal Defects ◽

Diffraction Reflection ◽

Reaction Products ◽

Intermediate Energies ◽

Crystal Films ◽

Reflection Electron Microscopy

The formation of oxide structures on single crystal films of metals has been investigated using the REMEDIE system (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies) (1). Using this instrument scanning images can be obtained with a 5 to 15keV incident electron beam by collecting either secondary or diffracted electrons from the crystal surface (2). It is particularly suited to studies of the present sort where the surface reactions are strongly related to surface morphology and crystal defects and the growth of reaction products is inhomogeneous and not adequately described in terms of a single parameter. Observation of the samples has also been made by reflection electron diffraction, reflection electron microscopy and replication techniques in a JEM-100B electron microscope.A thin single crystal film of copper, epitaxially grown on NaCl of (100) orientation, was repositioned on a large copper single crystal of (111) orientation.

Download Full-text

Zero-loss omega-filtered REM and RHEED on the new Zeiss 912

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087392 ◽

1991 ◽

Vol 49 ◽

pp. 616-617

Author(s):

J.C.H. Spence ◽

J. Mayer

Keyword(s):

Electron Microscopy ◽

Materials Science ◽

Surface States ◽

Ccd Camera ◽

Dark Field ◽

Ion Pump ◽

Magnetic Imaging ◽

Reflection Electron Microscopy ◽

Diffraction Patterns ◽

Large Background

The Zeiss 912 is a new fully digital, side-entry, 120 Kv TEM/STEM instrument for materials science, fitted with an omega magnetic imaging energy filter. Pumping is by turbopump and ion pump. The magnetic imaging filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. The energy loss intensity distribution may also be displayed on the screen, and recorded by scanning it over the PMT supplied. If a CCD camera is fitted and suitable new software developed, “parallel ELS” recording results. For large fields of view, filtered images can be recorded much more efficiently than by Scanning Reflection Electron Microscopy, and the large background of inelastic scattering removed. We have therefore evaluated the 912 for REM and RHEED applications. Causes of streaking and resonance in RHEED patterns are being studied, and a more quantitative analysis of CBRED patterns may be possible. Dark field band-gap REM imaging of surface states may also be possible.

Download Full-text

The annealed (0001) α-alumina surface and its influence on thin-film growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138051 ◽

1995 ◽

Vol 53 ◽

pp. 336-337

Author(s):

Michael W. Bench ◽

Paul G. Kotula ◽

C. Barry Carter

Keyword(s):

Electron Microscopy ◽

Surface Energy ◽

Film Growth ◽

Thin Film Growth ◽

Energy Calculations ◽

Transmission Electron ◽

Reflection Electron Microscopy ◽

Low Energy Electron ◽

Surface Nature

The growth of semiconductors, superconductors, metals, and other insulators has been investigated using alumina substrates in a variety of orientations. The surface state of the alumina (for example surface reconstruction and step nature) can be expected to affect the growth nature and quality of the epilayers. As such, the surface nature has been studied using a number of techniques including low energy electron diffraction (LEED), reflection electron microscopy (REM), transmission electron microscopy (TEM), molecular dynamics computer simulations, and also by theoretical surface energy calculations. In the (0001) orientation, the bulk alumina lattice can be thought of as a layered structure with A1-A1-O stacking. This gives three possible terminations of the bulk alumina lattice, with theoretical surface energy calculations suggesting that termination should occur between the Al layers. Thus, the lattice often has been described as being made up of layers of (Al-O-Al) unit stacking sequences. There is a 180° rotation in the surface symmetry of successive layers and a total of six layers are required to form the alumina unit cell.

Download Full-text

SREM observation of the interaction between the in-situ deposited Pd small particles and MgO cleavage surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143523 ◽

1986 ◽

Vol 44 ◽

pp. 382-383

Author(s):

H.-J. Ou

Keyword(s):

Electron Microscopy ◽

Small Particle ◽

Small Particles ◽

Cleavage Surface ◽

Metallic Particles ◽

Microscopy Technique ◽

Ceramic Surfaces ◽

Reflection Electron Microscopy ◽

New Perspective

The understanding of the interactions between the small metallic particles and ceramic surfaces has been studied by many catalyst scientists. We had developed Scanning Reflection Electron Microscopy technique to study surface structure of MgO hulk cleaved surface and the interaction with the small particle of metals. Resolutions of 10Å has shown the periodic array of surface atomic steps on MgO. The SREM observation of the interaction between the metallic particles and the surface may provide a new perspective on such processes.

Download Full-text

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135599 ◽

1990 ◽

Vol 48 (2) ◽

pp. 398-399

Author(s):

M. Gajdardziska-Josifovska

Keyword(s):

Electron Microscopy ◽

High Energy ◽

Two Dimensional ◽

High Energy Electron ◽

Reflection And Transmission ◽

Experimental Diffraction Pattern ◽

Surface Resonance ◽

Reconstructed Surfaces ◽

Reflection Electron Microscopy ◽

Convergent Beam

Parabolas have been observed in the reflection high-energy electron diffraction (RHEED) patterns from surfaces of single crystals since the early thirties. In the last decade there has been a revival of attempts to elucidate the origin of these surface parabolas. The renewed interest stems from the need to understand the connection between the parabolas and the surface resonance (channeling) condition, the latter being routinely used to obtain higher intensity in reflection electron microscopy (REM) images of surfaces. Several rather diverging descriptions have been proposed to explain the parabolas in the reflection and transmission Kikuchi patterns. Recently we have developed an unifying general treatment in which the parabolas are shown to be K-lines of two-dimensional lattices. Here we want to review the main features of this description and present an experimental diffraction pattern from a 30° MgO (111) surface which displays parabolas that can be attributed to the surface reconstruction.

Download Full-text

Reflection electron microscopy of as-grown diamond surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150861 ◽

1993 ◽

Vol 51 ◽

pp. 1006-1007

Author(s):

Z.L. Wang ◽

J. Bentley ◽

R.E. Clausing ◽

L. Heatherly ◽

L.L. Horton

Keyword(s):

Electron Microscopy ◽

Synthetic Diamond ◽

High Energy ◽

Dark Field ◽

Reverse Direction ◽

Diamond Surfaces ◽

Grain Sizes ◽

Synthetic Diamonds ◽

De Beers ◽

Reflection Electron Microscopy

It has been found that the abrasion of diamond-on-diamond depends on the crystal orientation. For a {100} face, the friction coefficient for sliding along <011> is much higher than that along <001>. For a {111} face, the abrasion along <11> is different from that in the reverse direction <>. To interpret these effects, a microcleavage mechanism was proposed in which the {100} and {111} surfaces were assumed to be composed of square-based pyramids and trigonal protrusions, respectively. Reflection electron microscopy (REM) has been applied to image the microstructures of these diamond surfaces.{111} surfaces of synthetic diamond:The synthetic diamonds used in this study were obtained from the De Beers Company. They are in the as-grown condition with grain sizes of 0.5-1 mm without chemical treatment or mechanical polishing. By selecting a strong reflected beam in the reflection high-energy electron diffraction (RHEED) pattern, the dark-field REM image of the surface is formed (Fig. 1).

Download Full-text

Contrasts of planar defects in reflection electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015085x ◽

1993 ◽

Vol 51 ◽

pp. 1004-1005

Author(s):

Feng Tsai ◽

J. M. Cowley

Keyword(s):

Electron Microscopy ◽

Surface Defects ◽

Practical Importance ◽

Theoretical Treatment ◽

Crystal Surfaces ◽

Planar Defects ◽

Surface Steps ◽

Surface Reconstructions ◽

Domain Boundaries ◽

Reflection Electron Microscopy

Reflection electron microscopy (REM) has been used to study surface defects such as surface steps, dislocations emerging on crystal surfaces, and surface reconstructions. However, only a few REM studies have been reported about the planar defects emerging on surfaces. The interaction of planar defects with surfaces may be of considerable practical importance but so far there seems to be only one relatively simple theoretical treatment of the REM contrast and very little experimental evidence to support its predications. Recently, intersections of both 90° and 180° ferroelectric domain boundaries with BaTiO3 crystal surfaces have been investigated by Tsai and Cowley with REM.The REM observations of several planar defects, such as stacking faults and domain boundaries have been continued by the present authors. All REM observations are performed on a JEM-2000FX transmission electron microscope. The sample preparations may be seen somewhere else. In REM, the incident electron beam strikes the surface of a crystal with a small glancing angle.

Download Full-text

Experiments on REM and SREM using a Tem/Stem Microscope with a Configurable Angle-Resolving Detector

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180446 ◽

1990 ◽

Vol 48 (1) ◽

pp. 338-339

Author(s):

H. Banzhof ◽

I. Daberkow

Keyword(s):

Electron Microscopy ◽

Single Crystal ◽

Crystal Surface ◽

High Energy ◽

Contrast Effects ◽

Atomic Steps ◽

Single Crystal Surfaces ◽

Platinum Single Crystal ◽

Reflection Electron Microscopy ◽

Beam Reflection

A Philips EM 420 electron microscope equipped with a field emission gun and an external STEM unit was used to compare images of single crystal surfaces taken by conventional reflection electron microscopy (REM) and scanning reflection electron microscopy (SREM). In addition an angle-resolving detector system developed by Daberkow and Herrmann was used to record SREM images with the detector shape adjusted to different details of the convergent beam reflection high energy electron diffraction (CBRHEED) pattern.Platinum single crystal spheres with smooth facets, prepared by melting a thin Pt wire in an oxyhydrogen flame, served as objects. Fig. 1 gives a conventional REM image of a (111)Pt single crystal surface, while Fig. 2 shows a SREM record of the same area. Both images were taken with the (555) reflection near the azimuth. A comparison shows that the contrast effects of atomic steps are similar for both techniques, although the depth of focus of the SREM image is reduced as a result of the large illuminating aperture. But differences are observed at the lengthened images of small depressions and protrusions formed by atomic steps, which give a symmetrical contrast profile in the REM image, while an asymmetric black-white contrast is observed in the SREM micrograph. Furthermore the irregular structures which may be seen in the middle of Fig. 2 are not visible in the REM image, although it was taken after the SREM record.

Download Full-text