Double Crystal X-Ray Diffraction Measurement of a Triclinicly Distorted and Tilted AlxGa1-xAs Unit Cell Produced by Growth on Offcut GaAs Substrates

1989 ◽  
Vol 159 ◽  
Author(s):  
A. Leiberich ◽  
J. Levkoff
Keyword(s):  
Strain Relaxation ◽  
Growth Direction ◽  
Unit Cell ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Additional Cell ◽  
Additional Strain ◽  
Film Substrate

ABSTRACTCorrections are required for double crystal X-ray diffraction characterization of epitaxial AlxGa1-xAs layers grown on offcut GaAs (100) substrates. Double crystal X-ray diffraction measurements show that the cubic film unit cell defined by Vegard's law is triclinicly distorted and tilted with respect to the substrate unit cell. The distortion and tilt angles oppose each other defining a crystal geometry where the substrate and film <100= axes remain approximately coplanar with the surface normal. This film/substrate crystal geometry leads to formulation of a model describing heteroepitaxy on offcut (100) substrates. When film atoms are bonded to an offcut substrate, the already tetragonaly distorted film unit cell is subjected to additional cell distortions. The magnitude of this additional strain depends on where the film atoms are positioned on a substrate terrace. The first few layers of film atoms establish swain grades across individual substrate terraces. Constrained by the geometry of this interface region and driven by strain relaxation in the net growth direction, subsequent heteroepitaxy forms the measured film/substrate crystal geometry.

Strain relaxation studied by photoluminescence and by double crystal X-ray diffraction measurements in strained InGaAs

1994 ◽  
Vol 22 (2-3) ◽  
pp. 222-226 ◽  
Author(s):  
A. Tabata ◽  
T. Benyattou ◽  
G. Guillot ◽  
S.A. Clark ◽  
J.E. Macdonald ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray

Raman and X-ray diffraction study of relaxation in Si–Si1–xGex strained-layer superlattices

1989 ◽  
Vol 67 (4) ◽  
pp. 351-357 ◽  
Author(s):  
D. J. Lockwood ◽  
J.-M. Baribeau ◽  
P. Y. Timbrell
Keyword(s):  
Sharp Decrease ◽  
Growth Direction ◽  
Longitudinal Optical ◽  
Acoustic Mode ◽  
Progressive Relaxation ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Raman Scattering Spectroscopy ◽  
X Ray

We report a study of the relaxation of Si–Si1–xGex strained single layers and superlattices by Raman scattering spectroscopy, double crystal X-ray diffraction, and transmission and scanning electron microscopy. Samples of various dimensions and compositions were produced by molecular beam epitaxy at a growth temperature of 500 ± 30 °C. The thermal stability of the various specimens was investigated by annealing experiments at temperatures between 600 and 900 °C. Considerable deterioration of the crystal quality and progressive relaxation were observed in some of the samples. Relaxation occurred through formation of misfit dislocations at the first Si–Si1–xGex interface and these caused threading dislocations to form within the epilayer. The degradation of the superlattice interfaces on annealing is correlated with a sharp decrease in the acoustic mode Raman intensities. Strain values perpendicular to the growth direction as a function of annealing temperature are obtained from a kinematical simulation of the X-ray rocking curves. These results are compared with the frequency shifts of the longitudinal optical phonons in the Raman spectra. The results obtained for the critical layer thicknesses versus x are consistent with the excess stress model of Tsao and co-workers.

Heterostructural Characterization of Pseudomorphic, Partially Strained, and Highly Mismatched Semiconductors Using Double Crystal X-Ray Diffraction, TEM, and SEM

1994 ◽  
Vol 340 ◽  
Author(s):  
Hyung Mun Kim ◽  
Sang-Gi Kim ◽  
Sahn Nahm ◽  
Hyung-Ho Park ◽  
Hae-Kwon Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
X Ray Diffraction ◽  
Gaas Sample ◽  
Double Crystal ◽  
Cross Sectional ◽  
X Ray ◽  
Peak Broadening

ABSTRACTHeterostructural properties of pseudomorphic (AlGaAs/GaAs), partially strained (GaInAs/GaAs), and highly strained (GaAs/Si) semiconductor systems have been studied using High Resolution Double-Crystal X-ray Diffraction (DXRD), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). Using the high resolution DXRD with CuKα1 and two-reflection Si (220) monochromator, we obtained (004) symmetric and (115) or (224) asymmetric reflection rocking curves for samples grown by molecular beam epitaxy. With 0.5 μm thick samples, perpendicular and in-plane lattice mismatches were calculated using elastic theory and compared with each other. The different degree of relaxation for these samples was observed and correlated with the lattice mismatch, X-ray layer peak broadening (i.e., full width at half maximum), and SEM surface morphology. For a GaInAs/GaAs sample, the strain relaxation along one of the <110> directions was more than the other direction, that is, the strain relaxation is not isotrophic. Also we observed that the lines were mainly parallel in one direction, i.e., they did not form a cross-hatch pattern. TEM images from both cross-sectional and planar views of the samples will be presented.

Homogeneous Strain Relaxation and Mosaic Spread in InGaAs/GaAs Heterostructures Using Triple Axis Diffractometry

1994 ◽  
Vol 38 ◽  
pp. 221-226
Author(s):  
M. S. Goorsky ◽  
K. M. Matney ◽  
G. Chu ◽  
R. S. Goldman ◽  
K. L. Kavanagh
Keyword(s):  
Strain Relaxation ◽  
Growth Direction ◽  
Indium Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mosaic Spread ◽  
Peak Broadening ◽  
High Indium Content ◽  
Crystallographic Tilt ◽  
Homogeneous Strain

Abstract We investigated strain relaxation in (001) InGaAs/GaAs structures using both double and triple axis high resolution x-ray diffraction techniques. We determined diat broadening which is observed in double axis scans stews pnmanly from mosaic spread and not from lattice constant variations in the layer, demonstrating that relaxation is uniform along the growth direction. These observations held for layers with both low and high indium content and extents of relaxation. Triple axis measurements showed that the peak broadening was due exclusively to mosaic spread for the low indium content samples and also confirmed earlier double axis measurements that a crystallographic tilt of the epitaxial layer was attributed to substrate miscut. The ability to distinguish the source of peak broadening and crystallographic tilts makes triple axis diffraction a powerful characterization technique for the study of mismatched epitaxial layers.

scholarly journals Структура и оптические характеристики пленок ниобатов бария-стронция на подложках Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=-

2019 ◽  
Vol 126 (5) ◽  
pp. 568
Author(s):  
А.В. Павленко ◽  
С.В. Кара-Мурза ◽  
А.П. Корчикова ◽  
А.А. Тихий ◽  
Д.В. Стрюков ◽  
...  
Keyword(s):  
Cell Parameter ◽  
Rf Sputtering ◽  
Film Surface ◽  
Growth Direction ◽  
Relaxor Ferroelectric ◽  
X Ray Diffraction ◽  
Crystal Axis ◽  
X Ray ◽  
Free Film ◽  
Film Substrate

AbstractThe structure and optical characteristics of thin films of relaxor ferroelectric Ba_0.5Sr_0.5Nb_2O_6 grown by RF sputtering in an oxygen atmosphere on an Al_2O_3 substrate ( c cut) have been studied. X-ray diffraction analysis shows that Ba_0.5Sr_0.5Nb_2O_6 films are c -oriented and unit-cell parameter c is 3.948(1) Å. Ellipsometric measurements confirm that SBN-50 films are characterized by a natural growth direction, which coincides with the direction of the optical crystal axis. An analysis of ellipsometric results shows that there is no transition layer at the film/substrate interface; the damaged layer on the free film surface is 7.5 nm thick, and the volume filling factor is estimated to be 0.625.

Growth and Structural Characterization of Sr2TiO4: Chemical Control Over the Terminating SrTiO3 Surface.

1999 ◽  
Vol 587 ◽  
Author(s):  
P. A. Salvador ◽  
B. Mercey ◽  
O. Perez ◽  
A. M. Haghiri-Gosnet ◽  
T.-D. Doan ◽  
...  
Keyword(s):  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Control ◽  
Plane Film ◽  
Out Of Plane ◽  
Dimensional Growth ◽  
Laser Mbe ◽  
Film Substrate

AbstractThin films of Sr2TiO4 were grown using pulsed laser deposition (PLD) and laser-MBE on [100]-SrTiO3single crystal substrates. Films grown by standard PLD display only a single peak in the X-ray diffraction spectra, corresponding to the (006) peak of the K2NiF4 parent structure. Using a Laser-MBE, controlled two-dimensional growth and RHEED intensity oscillations can be routinely obtained. The period of the RHEED intensity oscillations was confirmed to correspond to the deposition of one-half the unit cell. In contrast to PLD-grown films, the (004) and (006) peaks are observed in XRD spectra for the Laser-MBE-grown films. The intensity of the (004) peak is discussed and modeled with respect to in-plane disorder arising from substrate step-edges and out-of-plane film-substrate structural mismatches. That a single, half unit-cell can be deposited allows one to "flip" the terminating surface of SrTiO3 in a controlled and simple manner from a pure TiO2 layer to a SrO layer. Experimental evidence of the importance of such surface control is given for the SrCuO2 structural stability.

Depth Dependence of Residual Strains in Textured Mo Thin Films Using High-Resolution X-Ray Diffraction

1995 ◽  
Vol 403 ◽  
Author(s):  
S. G. Malhotra ◽  
Z. U. Rek ◽  
S. M. Yalisove ◽  
J. C. Bilello
Keyword(s):  
High Resolution ◽  
Diffraction Method ◽  
Growth Direction ◽  
Elastic Model ◽  
Normal Strain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Dependence ◽  
Residual Strains ◽  
Film Substrate

AbstractThe magnitude of the average stress in a thin film can be obtained by measuring the curvature of the film-substrate couple. However, the details of the strain distribution, as a function of depth through the thickness of the film, can have important consequences in governing film quality and ultimate morphology. A high-resolution x-ray diffraction method was used to determine the depth dependence of strain in a textured Mo film, with a nominal thickness of 260 nm, which was deposited by planar magnetron sputtering onto Si (100) substrates. The principal strains, resolved onto a laboratory reference frame, displayed a negligible gradient in the azimuthal directions (x and y), but displayed a large gradient in the direction normal to the film (z). A similar trend was previously observed for a 100 nm polycrystalline film, but the magnitude of the normal strain very near the free surface was about a factor of 2 less. The increase in the normal strain may be due to the development of a preferred growth direction and grain facetting. A linear elastic model was also used to determine the strains in successive slabs of the film, where strain variations between slabs were indicated.

Fabrication and study the effect of the laser on the properties of the compound Tl2-xHgxBa2-ySryCa2Cu3O10+δ superconductor

2018 ◽  
pp. 168
Author(s):  
A. Kareem Dahash Ali ◽  
Nihad Ali Shafeek
Keyword(s):  
Transition Temperature ◽  
Solid State ◽  
Hydrostatic Pressure ◽  
Electrical Properties ◽  
Co2 Laser ◽  
Temperature Shift ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural And Electrical Properties

This study included the fabrication of    compound (Tl2-xHgxBa2-ySryCa2Cu3O10+δ) in a manner solid state and under hydrostatic pressure ( 8 ton/cm2) and temperature annealing(850°C), and determine the effect of the laser on the structural and electrical properties elements in the compound, and various concentrations of x where (x= 0.1,0.2,0.3 ). Observed by testing the XRD The best ratio of compensation for x is 0.2 as the value of a = b = 5.3899 (A °), c = 36.21 (A °) show that the installation of four-wheel-based type and that the best temperature shift is TC= 142 K  .When you shine a CO2 laser on the models in order to recognize the effect of the laser on these models showed the study of X-ray diffraction of these samples when preparing models with different concentrations of the values ​​of x, the best ratio of compensation is 0.2 which showed an increase in the values ​​of the dimensions of the unit cell a=b = 5.3929 (A °), c = 36.238 (A°). And the best transition temperature after shedding laser is TC=144 K. 

scholarly journals X-ray Diffraction Analysis and Williamson-Hall Method in USDM Model for Estimating More Accurate Values of Stress-Strain of Unit Cell and Super Cells (2 × 2 × 2) of Hydroxyapatite, Confirmed by Ultrasonic Pulse-Echo Test

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2949
Author(s):  
Marzieh Rabiei ◽  
Arvydas Palevicius ◽  
Amir Dashti ◽  
Sohrab Nasiri ◽  
Ahmad Monshi ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Ultrasonic Pulse ◽  
High Accuracy ◽  
Unit Cell ◽  
Deformation Model ◽  
X Ray Diffraction ◽  
Uniform Deformation ◽  
X Ray ◽  
Pulse Echo

Taking into account X-ray diffraction, one of the well-known methods for calculating the stress-strain of crystals is Williamson-Hall (W–H). The W-H method has three models, namely (1) Uniform deformation model (UDM); (2) Uniform stress deformation model (USDM); and (3) Uniform deformation energy density model (UDEDM). The USDM and UDEDM models are directly related to the modulus of elasticity (E). Young’s modulus is a key parameter in engineering design and materials development. Young’s modulus is considered in USDM and UDEDM models, but in all previous studies, researchers used the average values of Young’s modulus or they calculated Young’s modulus only for a sharp peak of an XRD pattern or they extracted Young’s modulus from the literature. Therefore, these values are not representative of all peaks derived from X-ray diffraction; as a result, these values are not estimated with high accuracy. Nevertheless, in the current study, the W-H method is used considering the all diffracted planes of the unit cell and super cells (2 × 2 × 2) of Hydroxyapatite (HA), and a new method with the high accuracy of the W-H method in the USDM model is presented to calculate stress (σ) and strain (ε). The accounting for the planar density of atoms is the novelty of this work. Furthermore, the ultrasonic pulse-echo test is performed for the validation of the novelty assumptions.

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