Metal Deposition by High-Energy Sputtering for High Magnification Electron Microscopy

1986 ◽  
pp. 101-166 ◽  
Author(s):  
K.-R. Peters
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Metal Deposition ◽  
High Magnification

Effects of High-Energy Ions on Synthetic Quartz

1972 ◽  
Vol 30 ◽  
pp. 544-545
Author(s):  
Joseph J. Comer ◽  
Charles Bergeron ◽  
Lester F. Lowe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
High Energy ◽  
Transmission Electron ◽  
Kikuchi Lines ◽  
High Energy Ions ◽  
Diffraction Patterns ◽  
Dauphiné Twinning ◽  
Beam Damage

Using a Van De Graaff Accelerator thinned specimens were subjected to bombardment by 3 MeV N+ ions to fluences ranging from 4x1013 to 2x1016 ions/cm2. They were then examined by transmission electron microscopy and reflection electron diffraction using a 100 KV electron beam.At the lowest fluence of 4x1013 ions/cm2 diffraction patterns of the specimens contained Kikuchi lines which appeared somewhat broader and more diffuse than those obtained on unirradiated material. No damage could be detected by transmission electron microscopy in unannealed specimens. However, Dauphiné twinning was particularly pronounced after heating to 665°C for one hour and cooling to room temperature. The twins, seen in Fig. 1, were often less than .25 μm in size, smaller than those formed in unirradiated material and present in greater number. The results are in agreement with earlier observations on the effect of electron beam damage on Dauphiné twinning.

High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

1995 ◽  
Vol 53 ◽  
pp. 524-525
Author(s):  
Z. Horita ◽  
D. J. Smith ◽  
M. Furukawa ◽  
M. Nemoto ◽  
R. Z. Valiev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
High Resolution ◽  
Grain Boundaries ◽  
Energy State ◽  
High Energy ◽  
Grain Structure ◽  
Boundary Structure ◽  
Solid Solution Alloy ◽  
Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

Parabolas from Reconstructed Surfaces Observed in Convergent-Beam RHEED Patterns

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.

Transmission Electron Microscopy of Epitaxial silicides grown by ultra high vacuum deposition

1989 ◽  
Vol 47 ◽  
pp. 462-463
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Transmission Electron

The silicides CoSi2 and NiSi2 are both metallic with the fee flourite structure and lattice constants which are close to silicon (1.2% and 0.6% smaller at room temperature respectively) Consequently epitaxial cobalt and nickel disilicide can be grown on silicon. If these layers are formed by ultra high vacuum (UHV) deposition (also known as molecular beam epitaxy or MBE) their thickness can be controlled to within a few monolayers. Such ultrathin metal/silicon systems have many potential applications: for example electronic devices based on ballistic transport. They also provide a model system to study the properties of heterointerfaces. In this work we will discuss results obtained using in situ and ex situ transmission electron microscopy (TEM).In situ TEM is suited to the study of MBE growth for several reasons. It offers high spatial resolution and the ability to penetrate many monolayers of material. This is in contrast to the techniques which are usually employed for in situ measurements in MBE, for example low energy electron diffraction (LEED) and reflection high energy electron diffraction (RHEED), which are both sensitive to only a few monolayers at the surface.

Reflection electron microscopy of as-grown diamond surfaces

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).

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

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.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

scholarly journals Effects of Recycled Fe2O3 Nanofiller on the Structural, Thermal, Mechanical, Dielectric, and Magnetic Properties of PTFE Matrix

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2332
Author(s):  
Ahmad Mamoun Khamis ◽  
Zulkifly Abbas ◽  
Raba’ah Syahidah Azis ◽  
Ebenezer Ekow Mensah ◽  
Ibrahim Abubakar Alhaji
Keyword(s):  
Electron Microscopy ◽  
High Energy ◽  
Filler Loading ◽  
Complex Permeability ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Energy Ball ◽  
Hematite Fe2o3 ◽  
Ptfe Composites

The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5–25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3–PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector network analyzer (VNA) in the frequency range 8.2–12.4 GHz. The CTE of PTFE matrix decreased from 65.28×10−6/°C to 39.84×10−6/°C when the filler loading increased to 25 wt %. The real (ε′) and imaginary (ε″) parts of permittivity increased with the rFe2O3 loading and reached maximum values of 3.1 and 0.23 at 8 GHz when the filler loading was increased from 5 to 25 wt %. A maximum complex permeability of 1.1−j0.07 was also achieved by 25 wt % nanocomposite at 10 GHz.

Interaction Between Basal Stacking Faults and Prismatic Inversion Domain Boundaries in GaN

2000 ◽  
Vol 639 ◽  
Author(s):  
Philomela Komninou ◽  
Joseph Kioseoglou ◽  
Eirini Sarigiannidou ◽  
George P. Dimitrakopulos ◽  
Thomas Kehagias ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Stacking Faults ◽  
High Resolution Electron Microscopy ◽  
High Energy ◽  
Low Energy ◽  
Inversion Domain ◽  
Resolution Electron ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

ABSTRACTThe interaction of growth intrinsic stacking faults with inversion domain boundaries in GaN epitaxial layers is studied by high resolution electron microscopy. It is observed that stacking faults may mediate a structural transformation of inversion domain boundaries, from the low energy types, known as IDB boundaries, to the high energy ones, known as Holt-type boundaries. Such interactions may be attributed to the different growth rates of adjacent domains of inverse polarity.

Microstructure and superconducting properties of attrition-milled Bi2Sr2CaCu2Ox

1994 ◽  
Vol 9 (2) ◽  
pp. 297-304 ◽  
Author(s):  
J.S. Luo ◽  
H.G. Lee ◽  
S.N. Sinha
Keyword(s):  
Electron Microscopy ◽  
Milled Powder ◽  
High Energy ◽  
Double Layers ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Steel Tank ◽  
Practical Implications

The microstructure and superconducting properties of Bi2Sr2CaCu2Ox (Bi-2212) during high-energy attrition milling were investigated in detail by a combination of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and magnetization techniques. The starting superconducting powder was milled in a standard laboratory attritor using yttria-stabilized ZrO2 balls and a stainless steel tank. After selected time increments, the milling was interrupted and a small quantity of milled powder was removed for further analysis. It was found that the deformation process rapidly refines Bi-2212 into nanometer-size crystallites, increases atomic-level strains, and changes the plate-like morphology of Bi-2212 to granular submicron clusters. At short milling times, the deformation seems localized at weakly linked Bi-O double layers, leading to twist/cleavage fractures along the {001} planes. The Bi-2212 phase decomposes into several bismuth-based oxides and an amorphous phase after excessive deformation. The superconducting transition is depressed by about 10 K in the early stages of milling and completely vanishes upon prolonged deformation. A deformation mechanism is proposed and correlated with the evolution of superconducting properties. The practical implications of these results are presented and discussed.

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