Relaxation of Metamorphic III-V Heterostructures Studied by Digital Processing of HREM Images

1998 ◽  
Vol 523 ◽  
Author(s):  
André Rocher ◽  
Etienne Snoeck ◽  
Léon Goldstein ◽  
Joël Jacquet ◽  
Catherine Fortin
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Transition Zone ◽  
Epitaxial Layer ◽  
Digital Processing ◽  
High Resolution Electron Microscopy ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Misfit Stress ◽  
Resolution Electron

AbstractThe crystalline structure of metamorphic heterostructures grown by epitaxy has been studied by digital processing of High Resolution Electron Microscopy (HREM) images. Two systems have been investigated: the GaSb/(001)GaAs, known to be fully relaxed by a perfect Lomer dislocation network and the GaAs/(001)InP relaxed by partial and 60° dislocations randomly distributed. A transition zone can be defined between the perfect substrate and the relaxed epitaxial layer: its thickness is less than 20Å in GaSb/GaAs and more than 80Å in GaAs/InP. These results indicate that the misfit dislocations are only one of the elements involved in the relaxation of misfit stress.

HIGH RESOLUTION ELECTRON MICROSCOPE STUDY OF CdTe-Cd0.6Mn0.4 Te SUPERLATTICES

1985 ◽  
Vol 56 ◽  
Author(s):  
C. CHOI ◽  
N. OTSUKA ◽  
L. A. KOLODZIEJSKI ◽  
R. L. GUNSHOR-a
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Contrast ◽  
Electron Microscope Study ◽  
Lattice Mismatch ◽  
Thick Layer ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
High Resolution Electron Microscope

AbstractStructures of CdTe-Cd0.6Mn0.4Te superlattices which are caused by the lattice mismatch between suterlattice layers have been studied by high resolution electron microscopy (HREM). In thin-layer superlattices, the crystal lattice in each layeris elastically distorted, resulting in the change of the crystal symmetry from cubic to rhombohedral. The presence of the small rhombohedral distrotion has been confirmed through a phase contrast effect in HREM images. In a thick-layer superlattice, the lattice mismatch is accommodated by dissociated misfit dislocations. Burgers vectors of partial misfit dislocations have been identified from the shift of lattice fringes in HREM images.

High-resolution electron microscopy of epitaxial YBCO/Y2O3/YSZ on Si(001)

1993 ◽  
Vol 8 (9) ◽  
pp. 2112-2127 ◽  
Author(s):  
A. Bardal ◽  
O. Eibl ◽  
Th. Matthée ◽  
G. Friedl ◽  
J. Wecker
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Thick Layer ◽  
Atomic Layer ◽  
High Resolution Electron Microscopy ◽  
Stacking Fault ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Unit Cells

The microstructures of YBa2Cu3O7−δ (YBCO) thin films grown on Si with Y-stabilized ZrO2 (YSZ) and Y2O3 buffer layers were characterized by means of high-resolution electron microscopy. At the Si–YSZ interface, a 2.5 nm thick layer of regrown amorphous SiOx is present. The layer is interrupted by crystalline regions, typically 5 to 10 nm wide and 10 to 50 nm apart. Close to the crystalline regions, {111} defects are present in the Si substrate. The typical defect observed is an extrinsic stacking fault plus a perfect dislocation close to the stacking fault which terminates extra {111} planes in the upper part of the Si. These defects are probably formed by condensation of Si self-interstitials created during oxide regrowth. Precipitates are present in the Si close to the Si–YSZ interface and indicate that in-diffusion of Zr has occurred. The YSZ–Y2O3 interface is atomically sharp and essentially planar and contains no second phases. Perfect misfit dislocations with Burgers vector 1/2〈110〉 are present at this interface along with unrelaxed elastic misfit stresses. The Y2O3–YBCO interface is atomically sharp and planar, but contains steps. (001) stacking faults are present in the YBCO above these steps; the faults are, however, healed a few unit cells away from the interface. By HREM analysis of ultrathin specimen areas, the atomic layer of the YBCO closest to the Y2O3 was found to be a barium-oxygen layer.

High resolution electron microscopy of misfit dislocations in the GaAs/Si epitaxial interface

1986 ◽  
Vol 49 (5) ◽  
pp. 277-279 ◽  
Author(s):  
N. Otsuka ◽  
C. Choi ◽  
Y. Nakamura ◽  
S. Nagakura ◽  
R. Fischer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Epitaxial Interface

Transmission electron microscopy study of Co/Pd and Co/Au multilayers

1993 ◽  
Vol 8 (5) ◽  
pp. 1019-1027 ◽  
Author(s):  
F. Hakkens ◽  
A. De Veirman ◽  
W. Coene ◽  
Broeder F.J.A. den
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Columnar Structure ◽  
Electron Microscopy Study ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Resolution Electron

The structure of Co/Pd and Co/Au (111) multilayers is studied using transmission electron microscopy and high resolution electron microscopy. We focused on microstructure, atomic stacking (especially at the interfaces), and coherency, as these are structural properties that have considerable magnetic effects. A columnar structure with a strong curvature of the multilayer influenced by substrate temperature during growth is observed. High resolution imaging shows numerous steps at the interfaces of the multilayer structure and the presence of misfit dislocations. In bright-field images, periodic contrast fringes are observed at these interfaces as the result of moiré interference. These moiré fringes are used to study the misfit relaxation at the interfaces, whereas electron diffraction gives the average relaxation over the whole layer. Both measurements determined that, for Co/Pd as well as Co/Au multilayers, 80–85% of the misfit is relaxed and 20–15% remains in the form of strain, independent of the Co layer thickness in the regime studied.

High-Resolution Electron Microscopy of Olivine-Magnetite Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
Stuart Mckernan ◽  
C. Barry Carter ◽  
Daniel Ricoult ◽  
A. G. Cullis
Keyword(s):  
Electron Microscopy ◽  
Phase Transitions ◽  
High Resolution ◽  
Mass Transport ◽  
High Resolution Electron Microscopy ◽  
Model System ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
Lattice Images

ABSTRACTThe oxidation of iron-rich olivine to produce magnetite is a model system for the study of phase transitions involving mass transport. High-resolution lattice images of have been obtained from magnetite precipitates in naturally modified iron-rich olivines. The magnetite/olivine interface is shown to be extremely sharp. Steps and misfit dislocations are present at the interface.

Plan-view microstructures of Co/Ru bilayers

1995 ◽  
Vol 10 (6) ◽  
pp. 1539-1545 ◽  
Author(s):  
G.Z. Pan ◽  
A. Michel ◽  
V. Pierron-Bohnes ◽  
P. Vennéguès ◽  
M.C. Cadeville
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Image Contrast ◽  
Misfit Dislocations ◽  
Double Diffraction ◽  
Plan View ◽  
Resolution Electron ◽  
Diffraction Patterns

Plan-view microstructures of two Co/Ru bilayers with a composition of [Co12ÅRu45Å]2 and [Co40ÅRu35Å]2 have been studied by conventional and high resolution electron microscopy. Large differences in electron diffraction and image contrast between the two bilayers were observed, which are recognized as the microstructural variations during the relaxation of large coherent planar strains when the Co layers wet coherently or semicoherently the Ru layers. For the [Co12ÅRu45Å]2 bilayer, the Co layers are unrelaxed from the Ru layers; only one set of electron diffraction patterns was observed, and the image consists of three types of contrasts which are closely related with either the generation and movement of misfit dislocations or large coherent strains. For the [Co40ÅRu35Å]2 bilayer, the Co layers are relaxed basically from the Ru layers; two sets of electron diffraction patterns with double diffraction spots were observed, and the image consists of small irregular areas with moiré fringe dots.

Metastable Precipitates and their Misfit Strains in a Cu-0.9wt%Be Single Crystal

2007 ◽  
Vol 561-565 ◽  
pp. 2297-2300 ◽  
Author(s):  
Ryoichi Monzen ◽  
Toshiro Sakai ◽  
Chihiro Watanabe
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
High Resolution ◽  
Single Crystal ◽  
High Resolution Electron Microscopy ◽  
Length Change ◽  
Misfit Dislocations ◽  
Absolute Value ◽  
Resolution Electron ◽  
The Matrix

The precipitation processes from G.P. zones to γ’ in a Cu−0.9wt%Be alloy single crystal containing only the G.P. zones parallel to the matrix (001)α plane are investigated by high-resolution electron microscopy. The precipitate phases follow a G.P. zone → γ” → γI + γ’ sequence. The G.P. zone to γI phase transformation occurs successively via γ” during aging, while the γ’ phase heterogeneously precipitates on the γI phase. From length-change measurements during aging, the misfit strains of γ’ precipitates in directions perpendicular and parallel to [001]α are estimated as ε11 =ε22 = −0.03 and ε33 = −0.09, respectively. The observation that the estimated absolute value of ε33 is much smaller than that of ε33 = −0.25 calculated using lattice parameters of the γ’ phase and Cu matrix is understood in terms of the relaxation of ε33 by interfacial misfit dislocations.

Applications of high-resolution Electron Microscopy to semiconductor interfaces

1989 ◽  
Vol 47 ◽  
pp. 596-597
Author(s):  
H. L. Tsai
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Misfit Dislocation ◽  
Semiconductor Device ◽  
Diagnostic Technique ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Practical Applications ◽  
Semiconductor Interfaces ◽  
Resolution Electron

Practical applications of high-resolution electron microscopy (HREM) to semiconductor interfaces have been conducted in various areas. Among these are the use of the HREM as a diagnostic technique for interfacial quality, understanding of interfacial interactions, and analysis of misfit dislocations in heterostructures. These studies indicate that the HREM is a useful technique to provide in-depth understanding of interfaces for the process and defect controls.The quality of an interface often plays an important role in the film quality or the performance of a semiconductor device. Figure 1a shows one example illustrating the generation of threading dislocations from particles located at the lattice-mismatched In0.15Ga0.85As/GaAs interface. The HREM image shown in Fig. 1b indicates a particle to be located at a misfit dislocation. This observation suggests that a particle at the heterointerface can promote the nucleation of a dislocation and/or the formation of the misfit dislocation.

High-resolution electron microscopy of metal/metal and metal/metal-oxide interfaces in the Ag/Ni and Au/Ni systems

1990 ◽  
Vol 5 (9) ◽  
pp. 1995-2003 ◽  
Author(s):  
Y. Gao ◽  
Karl L. Merkle
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Metal Oxide ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Lattice Statics ◽  
Embedded Atom ◽  
Resolution Electron ◽  
Metal Metal

The atomic structures of heterophase interfaces with large misfits (>14% in Ag/Ni and Au/Ni) and with small misfits (∼2% in Ag/NiO and Au/NiO) have been studied by high-resolution electron microscopy (HREM). It is found that all interfaces are strongly faceted on (111) planes. This indicates that (111) interfaces have the lowest interfacial energy in both metal/metal and metal/metal-oxide systems. For the metal interfaces, this also agrees with determinations of interfacial energies by lattice statics calculations. The large misfit of Ag/Ni and Au/Ni interfaces is accommodated by misfit dislocations. Observations of misfit localization by HREM are in good agreement with images derived from computer simulation, based on relaxed structures, obtained in embedded atom calculations. All misfit dislocations at the Ag/Ni and Au/Ni interfaces lie exactly in the plane of the interfaces, while the dislocations at Ag/NiO and Au/NiO interfaces reside at a stand-off distance, 3 to 4 (111)Ag or (111)Au interplanar spacings from the interfaces.

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