Measurement of Elastic Lattice Distortion in PbTe/PbSnTe - Strained Layer Superlatices by Asymmetric High Angle X-ray interfernces

1985 ◽  
Vol 29 ◽  
pp. 367-374
Author(s):  
E. J. Fantner
Keyword(s):  
Elastic Strain ◽  
Lattice Mismatch ◽  
Strain Tensor ◽  
Misfit Strain ◽  
High Angle ◽  
Double Crystal ◽  
X Ray ◽  
Strained Layer ◽  
Thermal Expansion Coefficients ◽  
Quaternary Compounds

AbstractElastic strain significantly affects the electric and optical properties of PbTe/Pb1-xSnxTe - strained-layer superlattices. In the range of 10 - 350K the temperature dependence of the elastic strain present in these superlattices was measured by double-crystal x-ray diffraction. For superlattice periods smaller than 100nm High-angle x-ray interferences were observed. Using a novel method, which makes use of the High-angle interferences both for symmetrical as well as for asymmetrical reflections in a theta-twotheta scan with a narrow detector slit, the relative inclination of equivalent lattice planes due the elastic strain was measured. The components of the complete strain tensor of the constituent layers can be determined seperately even if their unstrained lattice constants are not known with sufficient accuracy as is the case in ternary and quaternary compounds. The lattice mismatch of up to 0.4% for Sn-contents smaller than 20% was found to be accommodated almost completely by elastic misfit strain. The amount of strain is shared between the constituent layers inversely to their relative thicknesses as long as the superlattice as a whole is much thicker than the buffer layer. Below room temperature an additional temperature dependent tensile strain due to differnt thermal expansion coefficients of the film and the BaF2-substrate is measured quantitatively.

X-Ray Strain Measurements in IV-VI Semiconductor Super-Lattices at Low Temperature

1983 ◽  
Vol 27 ◽  
pp. 171-178 ◽  
Author(s):  
E.J. Fantner ◽  
H. Clemens ◽  
G. Bauer
Keyword(s):  
Thin Films ◽  
Vapor Deposition ◽  
Tensile Strain ◽  
Room Temperature ◽  
Lattice Mismatch ◽  
Misfit Strain ◽  
Strain Measurements ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

AbstractMultilayers composed of many thin films of PbTe and Pb1-xSnxTe on BaF2 substrates were grown epitaxially by hot-wall-vapor deposition. In order to investigate the fraction of the total misfit (2.5x10-3 at x=O, 12) accommodated by misfit strain we have performed strain measurements on these superlattices by two different X-ray diffractometer techniques. We also report on substrate induced strain due to different thermal expansion coefficients of films and substrate. For film thicknesses smaller than 300 nm there is clear evidence for almost complete accommodation of lattice mismatch by misfit strain. Below room temperature the substrate induces a tensile strain which is comparable to that of the misfit strain.

X-ray diffraction study of a one-dimensional GaAs–AlAs superlattice

1977 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
A. Segmüller ◽  
P. Krishna ◽  
L. Esaki
Keyword(s):  
Elastic Strain ◽  
Lattice Mismatch ◽  
Reciprocal Lattice ◽  
Unit Cell ◽  
Scattering Data ◽  
High Angle ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Patterns

Low- and high-angle X-ray diffraction patterns have been obtained from one-dimensional superlattice crystals prepared artificially by alternately depositing predetermined thicknesses of GaAs and AlAs, on the (001) face of a GaAs single-crystal by molecular-beam epitaxy. The positions and intensities of several superlattice reflections obtained along the 00l, 11l and 02l reciprocal lattice rows have been recorded. The structure of the superlattice can be approximated by a model which incorporates elastic strains in the unit cell due to the lattice mismatch between GaAs and AlAs. The number of Ga and Al layers in the superlattice unit cell can be accurately determined from the low-angle scattering data while the relative intensities of the high-angle superlattice reflections are a sensitive measure of the elastic strain present in the lattice. It is shown that the elastic strain agrees with the value computed theoretically on the assumption that the strain is not relieved by dislocations at the GaAs–AlAs interfaces.

X-Ray Studies of GaAs/Si and ZnS/Si

1988 ◽  
Vol 144 ◽  
Author(s):  
H. M. Kim ◽  
Y-W Choi ◽  
S. Vernon ◽  
P. S. Moise ◽  
C. R. Wie
Keyword(s):  
Phase Contrast ◽  
Lattice Mismatch ◽  
Phase Contrast Microscopy ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Dislocation Densities ◽  
Contrast Microscopy ◽  
Expansion Coefficients

ABSTRACTThe MOCVD-grown layers of GaAs/Si(001), InP/GaAs/Si(001), and ZnS/Si(111) were studied using X-ray rocking curve (XRC), double crystal topography (DCT), and Nomarski phase contrast microscopy. The layer qualities of GaAs/Si, InP/GaAs, and InP/GaAs/Si from the XRC full width at half maximum (FWHM) agreed well with these determined from the Nomarski phase contrast microscopy. The in-plane lattice mismatch (parallel X-ray strain) was 3.71% for GaAs/Si. In the double heteroepitaxial layer (InP/GaAs/Si), the parallel X-ray strain of GaAs was 4.03% with respect to Si. The parallel X-ray strain was larger than the perpendicular X-ray strain in GaAs/Si, perhaps due to the mismatch in thermal expansion coefficients between GaAs and Si. Dislocation densities estimated from the rocking curve linewidth were 5.30 × 107 cm−2 for GaAs/Si, 3.27 × 108 cm−2 for InP/GaAs. We also present the double crystal X-ray topographs of the III-V/Si and II-VI/Si samples.

Thermal Strain Study of Almost Lattice-Matched Epitaxial InuGa1-uAs1-vP1-v Films on InP(100) Substrates

1989 ◽  
Vol 160 ◽  
Author(s):  
G. Bai ◽  
M-A. Nicolet ◽  
S.-J. Kim ◽  
R.G. Sobers ◽  
J.W. Lee ◽  
...  
Keyword(s):  
Room Temperature ◽  
Epitaxial Film ◽  
Lattice Mismatch ◽  
Thermal Strain ◽  
Growth Direction ◽  
Epitaxial Films ◽  
Double Crystal ◽  
X Ray ◽  
Lattice Matched ◽  
Coherent Interfaces

AbstractSingle layers of ~ 0.5µm thick InuGa1-uAs1-vPv (0.52 < u < 0.63 and 0.03 < v < 0.16) were grown epitaxially on InP(100) substrates by liquid phase epitaxy at ~ 630°C. The compositions of the films were chosen to yield a constant banndgap of ~ 0.8 eV (λ = 1.55 µm) at room temperature. The lattice mismatch at room temperature between the epitaxial film and the substrate varies from - 4 × 10-3 to + 4 × 10-3. The strain in the films was characterized in air by x-ray double crystal diffractometry with a controllable heating stage from 23°C to ~ 700°C. All the samples have an almost coherent interfaces from 23°C to about ~ 330°C with the lattice mismatch accomodated mainly by the tetragonal distortion of the epitaxial films. In this temperature range, the x-ray strain in the growth direction increases linearly with temperature at a rate of (2.0 ± 0.4) × 10-6/°C and the strain state of the films is reversible. Once the samples are heated above ~ 300°C, a significant irreversible deterioration of the epitaxial films sets in.

Submicrometre-resolution polychromatic three-dimensional X-ray microscopy

2012 ◽  
Vol 46 (1) ◽  
pp. 153-164 ◽  
Author(s):  
B. C. Larson ◽  
L. E. Levine
Keyword(s):  
Spatial Resolution ◽  
Elastic Strain ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Direct Determination ◽  
Phase Identification ◽  
Sn Whisker ◽  
X Ray ◽  
Elastic Strain Tensor

The ability to study the structure, microstructure and evolution of materials with increasing spatial resolution is fundamental to achieving a full understanding of the underlying science of materials. Polychromatic three-dimensional X-ray microscopy (3DXM) is a recently developed nondestructive diffraction technique that enables crystallographic phase identification, determination of local crystal orientations, grain morphologies, grain interface types and orientations, and in favorable cases direct determination of the deviatoric elastic strain tensor with submicrometre spatial resolution in all three dimensions. With the added capability of an energy-scanning incident beam monochromator, the determination of absolute lattice parameters is enabled, allowing specification of the complete elastic strain tensor with three-dimensional spatial resolution. The methods associated with 3DXM are described and key applications of 3DXM are discussed, including studies of deformation in single-crystal and polycrystalline metals and semiconductors, indentation deformation, thermal grain growth in polycrystalline aluminium, the metal–insulator transition in nanoplatelet VO2, interface strengths in metal–matrix composites, high-pressure science, Sn whisker growth, and electromigration processes. Finally, the outlook for future developments associated with this technique is described.

Digital X-Ray Rocking Curve Topography

1986 ◽  
Vol 82 ◽  
Author(s):  
T. S. Ananthanarayanan ◽  
R. G. Rosemeier ◽  
W. E. Mayo ◽  
J. H. Dinan
Keyword(s):  
Bragg Reflection ◽  
Strain Tensor ◽  
Epitaxial Films ◽  
Double Crystal ◽  
Rocking Curve ◽  
X Ray ◽  
Density Maps ◽  
First Time ◽  
Considerable Body ◽  
Double Crystal Diffractometer

SUMMARYThere is a considerable body of work available illustrating the significance of X-ray rocking curve measurements in micro-electronic applications. For the first time a high resolution (100-150µm) 2-dimensional technique called DARC (Digital Autcmated Rocking Curve) topography has been implemented. This method is an enhancement of the conventional double crystal diffractometer using a real time 2-dimensional X-ray detector.Several materials have been successfully examined using DARC topography. Same of these include: Si, GaAs, AlGaAs, InGaAs, HgMnTe, Al, Inconel, steels, etc. By choosing the appropriate Bragg reflection multi-layered micro-electronic structures have been analyzed nondestructively. Several epitaxial films, including HgCdTe and ZnCdTe, grown by molecular beam epitaxy, have also been characterized using iARC topography. The rocking curve half width maps can be translated to dislocation density maps with relative ease. This technique also allows the deconvolution of the micro-plastic lattice strain ccaponent from the total strain tensor.

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