A Weak Beam Imaging Technique for the Characterization of Interfacial Roughness in (InGa)As/GaAs Strained Layer Structures

1989 ◽  
Vol 159 ◽  
Author(s):  
J. Y. Yao ◽  
T. G. Andersson ◽  
G. L. Dunlop
Keyword(s):  
Imaging Technique ◽  
Interfacial Roughness ◽  
Strained Layers ◽  
Strained Layer ◽  
Weak Beam ◽  
Kinematic Theory ◽  
Transmission Electron ◽  
Layer Structures ◽  
Made In

ABSTRACTA transmission electron microscope weak beam imaging technique has been developed for the characterization of interfacial roughness in lattice strained (InGa)As/GaAs multiple layered structures. In this technique, the heterointerfaces of (100) type strained layers are imaged in an inclined projection with a g311 diffracted reflection at off-Bragg conditions which gives an enhanced contrast from variations in strained layer thickness. A calculation based on the kinematic theory of contrast was made in order to gain a better understanding of the contrast. The calculation suggests that the observed contrast is due to monolayer scale variations in thickness of the strained layers.

Interfacial Microstructures in InxGa1-xAs/GaAs Strained Layer Structures

1989 ◽  
Vol 148 ◽  
Author(s):  
J. Y. Yao ◽  
T. G. Andersson ◽  
G. L. Dunlop
Keyword(s):  
Molecular Beam ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Strained Layer ◽  
Weak Beam ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Layer Structures ◽  
Structural Imperfections ◽  
2D To 3D

ABSTRACTThe interfacial microstructures of lattice strained InxGal-xAs/GaAs multiple layer structures, that were grown by molecular beam epitaxy (MBE) on GaAs (100) substrates, have been investigated and characterised by transmission electron microscopy (TEM). A g3ii weak beam imaging technique has been used to study structural imperfections at the heterointerfaces. The morphology of rough heterointerfaces, which resulted from the growth of the InxGal-xAs layers (strained layer) either in a two dimensional (2D) or in a three dimensional (3D) growth mode via island formation, was imaged using this technique. A transition from 2D to 3D growth was found to occur at a certain critical layer thickness which decreased with increasing indium fraction. In thicker layers, dislocation complexes, which may have been caused bythe formation of islands, were also observed. These complexes were primarily composed ofstacking faults bounded by partial dislocations.

Solid Phase Epitaxy of Si1-xGex on Si Strained Layers

1989 ◽  
Vol 160 ◽  
Author(s):  
B.J. Robinson ◽  
B.T. Chilton ◽  
P. Ferret ◽  
D.A. Thompson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Strain Relaxation ◽  
Crystal Quality ◽  
Solid Phase Epitaxy ◽  
Strained Layers ◽  
Transmission Electron ◽  
Layer Structures

AbstractSingle strained layer structures of up to 30 nm of Si1-xGex. on (100) Si and capped with 30-36 nm of Si have been amorphized by implantation with 120 keV As . The amorphized region, extending to a depth of 130 nm, has been regrown by solid phase epitaxy (SPE) at 600°C. Characterization of the regrown structure by Rutherford backscattering/channeling techniques and transmission electron microscopy indicates that for x < 0.18 the SPE process results in the recovery of strain, while for x > 0.18 there is increasing strain relaxation and a deterioration of crystal quality.

Characterization of Dislocations in GaAs Grown on Si and Ge

1987 ◽  
Vol 91 ◽  
Author(s):  
N.-H. Cho ◽  
S. Mckernan ◽  
C. B. Carter ◽  
B. C. De Cooman ◽  
K. Wagner
Keyword(s):  
Lattice Mismatch ◽  
Imaging Technique ◽  
Layer Structure ◽  
Misfit Dislocations ◽  
Structure Model ◽  
Polar Material ◽  
Weak Beam ◽  
Transmission Electron ◽  
Prepared Layer

ABSTRACTDislocations are produced at the interface between epilayers and the substrate when there is a lattice mismatch. When GaAs is grown on Ge substrates, these dislocations can propagate into the epilayers. They can then interact with one another or with antiphase boundaries which are generated when the polar-material is grown on a non-polar materials.The interactions between these defects have been investigated using the weak-beam imaging technique of transmission electron microscopy. Possible interactions between the misfit dislocations and heterojunctions were examined in a specially prepared layer structure model of GaAs-AlxGal−xAs.

Characterization of Structure and Mechanical Properties of MoSi2-SiC Nanolayer Composites

1993 ◽  
Vol 322 ◽  
Author(s):  
H. Kung ◽  
T. R. Jervis ◽  
J-P. Hirvonen ◽  
M. Nastasi ◽  
T. E. Mitchell
Keyword(s):  
Mechanical Properties ◽  
Structural Changes ◽  
Crystallization Process ◽  
Mechanical Response ◽  
Cross Sectional ◽  
Annealing Conditions ◽  
Transmission Electron ◽  
Layer Structures ◽  
Amorphous Structures

AbstractA systematic study of the structure-mechanical properties relationship is reported for MoSi2-SiC nanolayer composites. Alternating layers of MoSi2 and SiC were synthesized by DCmagnetron and if-diode sputtering, respectively. Cross-sectional transmission electron microscopy was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures. Nanoindentation was employed to characterize the mechanical response as a function of the structural changes. As-sputtered material exhibits amorphous structures in both types of layers and has a hardness of 11GPa and a modulus of 217GPa. Subsequent heat treatment induces crystallization of MoSi2 to form the C40 structure at 500°C and SiC to form the a structure at 700°C. The crystallization process is directly responsible for the hardness and modulus increase in the multilayers. A hardness of 24GPa and a modulus of 340GPa can be achieved through crystallizing both MoSi2 and SiC layers. Annealing at 900°C for 2h causes the transformation of MoSi2 into the Cllb structure, as well as spheroidization of the layering to form a nanocrystalline equiaxed microstructure. A slight degradation in hardness but not in modulus is observed accompanying the layer break-down.

Structure Determination of Clusters Formed in Ultra-Low Energy High-Dose Implanted Silicon

2005 ◽  
Vol 108-109 ◽  
pp. 303-308 ◽  
Author(s):  
N. Cherkashin ◽  
Martin J. Hÿtch ◽  
Fuccio Cristiano ◽  
A. Claverie
Keyword(s):  
Electron Microscopy ◽  
Geometric Phase ◽  
Low Energy ◽  
High Dose ◽  
Dislocation Loops ◽  
Weak Beam ◽  
Transmission Electron ◽  
Geometric Phase Analysis

In this work, we present a detailed structural characterization of the defects formed after 0.5 keV B+ implantation into Si to a dose of 1x1015 ions/cm2 and annealed at 650°C and 750°C during different times up to 160 s. The clusters were characterized by making use of Weak Beam and High Resolution Transmission Electron Microscopy (HRTEM) imaging. They are found to be platelets of several nanometer size with (001) habit plane. Conventional TEM procedure based on defect contrast behavior was applied to determine the directions of their Burger’s vectors. Geometric Phase Analysis of HRTEM images was used to measure the displacement field around these objects and, thus, to unambiguously determine their Burger’s vectors. Finally five types of dislocation loops lying on (001) plane are marked out: with ] 001 [1/3 ≅ b and b ∝ [1 0 1], [-1 0 1], [0 1 1], [0 -1 1].

Planar Defects in Small Particles

1985 ◽  
Vol 43 ◽  
pp. 392-393
Author(s):  
R. Pérez ◽  
M. Avalos-Borja
Keyword(s):  
Stacking Faults ◽  
Particle Growth ◽  
Small Particles ◽  
Planar Defects ◽  
Metallic Particles ◽  
Weak Beam ◽  
Transmission Electron ◽  
Imaging Conditions

Transmission electron microscope techniques have been extensively used in the determination of the morphology of fine metallic particles. These techniques have been of particular importance in obtaining topographical information during particle growth and sintering. Thus, for example, it has been found that some of the most elementary forms consist of half cubo-octahedral units with (111) faces and (100) basis. Furthermore, full cubo-octahedral units have also been found, some of them showing stacking faults (SF) through the particles.It is important to point out that the characterization of this type of planar defects in small metallic particles has commonly been based on geometrical con. siderations. Additionally, the imaging conditions which have been used are the so-called weak beam (WB) diffraction conditions. Recent investigations have shown, on the other hand, that SF images under WB conditions present serious inconveniences, for example, contrast asymmetries in SF images which are not totally explained. Another difficulty with these WB fault images arises from twin boundaries which display image contrast similar to SF when a common reflection is strongly excited.

The Stability of Si-Si1-xGex Strained Layer Heterostructures.

1988 ◽  
Vol 130 ◽  
Author(s):  
D. C. Houghton ◽  
J-M. Baribeau ◽  
K. Song ◽  
D. D. Perovic
Keyword(s):  
Interference Microscopy ◽  
Layer System ◽  
Strained Layers ◽  
Strained Layer ◽  
Transmission Electron ◽  
Metastable Structures ◽  
Abrupt Changes ◽  
The Stability ◽  
Strained Layer Superlattices ◽  
Stability Limits

AbstractThe structural stability of strained layer superlattices (SLS's) is addressed using an equilibrium model and then compared to the stability of single strained layers. Relaxation mechanisms are described for various superlattice geometries. The application of a critical thickness/strain criterion to define stability limits was found to be very useful in predicting the detailed relaxation process. The competition between relaxation by misfit accommodation at the base of the SLS and at individual strained interfaces is considered for the initial condition of full coherency and after partial relaxation. Experimental data for the Si-Ge strained layer system are presented; as-grown by MBE and after annealing in the temperature range 500°C – 900°C. The extent of relaxation and the detailed dislocation structure within the SLS's were determined by X-ray rocking curve analysis, Nomarski interference microscopy and transmission electron microscopy. The abrupt changes in relaxation behaviour indicate that rigid boundaries between stable and metastable structures do exist, as predicted by the equilibrium models.

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