Measurement of strain in InGaN/GaN nanowires and nanopyramids

2015 ◽  
Vol 48 (2) ◽  
pp. 344-349 ◽  
Author(s):  
Tomaš Stankevič ◽  
Simas Mickevičius ◽  
Mikkel Schou Nielsen ◽  
Olga Kryliouk ◽  
Rafal Ciechonski ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Shell Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Shell Nanostructures ◽  
Vegard’S Law ◽  
Planar Films ◽  
The Individual

The growth and optoelectronic properties of core–shell nanostructures are influenced by the strain induced by the lattice mismatch between core and shell. In contrast with planar films, nanostructures contain multiple facets that act as independent substrates for shell growth, which enables different relaxation mechanisms. In this study, X-ray diffraction data are presented that show that InαGa1−αN shells grown on GaN cores are strained along each of the facets independently. Reciprocal space maps reveal multiple Bragg peaks, corresponding to different parts of the shell being strained along the individual facet planes. The strained lattice constants were found from the positions of the Bragg peaks. Vegard's law and Hooke's law for an anisotropic medium were applied in order to find the composition and strain in the InGaN shells. A range of nanowire samples with different InGaN shell thicknesses were measured and it is concluded that, with an In concentration of around 30%, major strain relaxation takes place when the thickness reaches 23 nm. InGaN shells of 6 and 9 nm thickness remain nearly fully strained biaxially along each of the \{10{\overline 1}0\} facets of the nanowires and the \{10{\overline 1}1\} facets of the nanopyramids.

Accurate Lattice Constant and Mismatch Measurements of SiC Heterostructures by X-Ray Multiple-Order Reflections

2002 ◽  
Vol 742 ◽  
Author(s):  
XianRong Huang ◽  
Michael Dudley ◽  
Philip G. Neudeck ◽  
J. Anthony Powell
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
Coherent Interface ◽  
Rocking Curve ◽  
X Ray ◽  
Lattice Planes ◽  
Atomically Flat

ABSTRACTHigh-resolution X-ray diffraction (HRXRD) combined with other diffraction techniques is applied to characterize 3C SiC epilayers hoteroepitaxially grown on atomically flat mesas on 4H and 6H SiC substrates. Small-beam rocking curve scan and reciprocal mapping show extremely high crystalline perfection and homogeneity of the ideally grown 3C-SiC epilayers. Accurate lattice measurements based on X-ray multiple-order reflections reveal that: 1) no misorientation between the (0001) lattice planes across the 4H/3C or 6H/3C interface is detected, confirming the 2D nucleation mechanism of the 3C epilayer from a flat coherent interface; 2) in-plane substrate/epilayer lattice mismatch always exists, but the 3C epilayers do not correspond to a completely relaxed cubic structure, indicating that the epilayers are partially strained; 3) lattice mismatch varies for different regions, implying a complicated strain relaxation mechanism of 3C epilayers on various mesas.

Lattice constant variation in GaN:Si layers grown by HVPE

2002 ◽  
Vol 743 ◽  
Author(s):  
A. Usikov ◽  
O. V. Kovalenkov ◽  
M. M. Mastro ◽  
D. V. Tsvetkov ◽  
A. I. Pechnikov ◽  
...  
Keyword(s):  
Defect Formation ◽  
Strain Relaxation ◽  
Growth Conditions ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Proper Selection ◽  
X Ray ◽  
Lattice Constants ◽  
Si Doping ◽  
Selection Of

ABSTRACTThe structural, optical, and electrical properties of HVPE-grown GaN-on-sapphire templates were studied. The c and a lattice constants of the GaN layers were measured by x-ray diffraction. It was observed that the c and a lattice constants vary non-monotonically with Si-doping. The proper selection of Si-doping level and growth conditions resulted in controllable strain relaxation, and thus, influenced defect formation in GaN-on-sapphire templates. It was also observed that HVPE homoepitaxial GaN layers grown on the templates have better crystal quality and surface morphology than the initial templates.

Thermoelectric properties of Tl9BiTe6 / Tl9BiSe6 solid solutions

2000 ◽  
Vol 626 ◽  
Author(s):  
Bernd Wölfing ◽  
Christian Kloc ◽  
Ernst Bucher
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
State Of The Art ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law

ABSTRACTThe compounds Tl9BiTe6 (TBT) and Tl9BiSe6 (TBS) crystallize in the tetragonal space group I4/mcm. Tl9BiTe6 has a thermopower of 185 μV/K and an electrical resistivity of 5.5 mΩcm at 300K, resulting in a power factor of S2/ρ = 0.6 mW/mK2. Compared to Bi2Te3 which is the state of the art material at this temperature this is about a factor of 7 lower. At 300 K TBS has a thermopower of 750 μV/K but a high resistivity of 130 Ωcm. To optimize the thermoelectric properties of TBT solid solutions have been formed with TBS. The resistivities and have been measured on Tl9BiTe1-xSex with x = 0.05, 0.08, 0.2 and 0.5. In addition to the electrical properties the lattice constants have been measured by X-ray diffraction. The dependence of the lattice constants on the Te/Se ratio clearly deviates from Vegard's law. Different affinities of Te and Se towards the two chalcogenide sites in the crystal can explain this behavior.

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.

scholarly journals CADEM: calculate X-ray diffraction of epitaxial multilayers

2017 ◽  
Vol 50 (1) ◽  
pp. 288-292 ◽  
Author(s):  
Paulina Komar ◽  
Gerhard Jakob
Keyword(s):  
Strain Relaxation ◽  
Diffraction Theory ◽  
Layer By Layer ◽  
Material System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Out Of Plane ◽  
Xrd Patterns ◽  
Epitaxial Multilayers

Epitaxial multilayers and superlattice (SL) structures are gaining increasing importance as they offer the opportunity to create artificial crystals with new functionalities. These crystals deviate from the parent bulk compounds not only in terms of the lattice constants but also in the symmetry classification, which renders calculation of their X-ray diffraction (XRD) patterns tedious. Nevertheless, XRD is essential to get information on the multilayer/SL structure such as, for example, out-of-plane lattice constants, strain relaxation and period length of the crystalline SL. This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary. Moreover, CADEM is very flexible and can be straightforwardly adapted to any material system. The source code of CADEM is available as supporting material for this article.

Microscopic phase stability of the dilute magnetic semiconductor Cd1−xFexSe

1993 ◽  
Vol 8 (6) ◽  
pp. 1348-1352 ◽  
Author(s):  
E. Klein ◽  
M. Homyonfer ◽  
W. Giriat ◽  
R. Tenne
Keyword(s):  
Solid Solution ◽  
Microprobe Analysis ◽  
Large Deviation ◽  
Large Strain ◽  
Magnetic Semiconductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
The Past ◽  
Vegard’S Law

The solubility of Fe in CdSe crystal has been studied in detail in the past. Using powder diffraction and atomic absorption spectroscopy, it was concluded that the upper limit for the solubility of iron in CdSe is 12–15%, and the actual Fe concentration in a solid solution agrees with the nominal Fe concentration (calculated from the concentration of the reactants). In the present study this question is re-examined using techniques that probe the average properties of the solid solution, such as x-ray diffraction, and techniques that probe the local structure and composition of the solid solution on the micron scale, such as energy and wavelength x-ray dispersive microprobe analysis. It is shown that the solubility of Fe in the CdSe matrix is appreciably smaller than the nominal value, and that microsegregation is obtained at a much lower Fe concentration than previously concluded. The immiscibility of Fe in this matrix is consistent with the large deviation of the lattice constants from Vegard's law. It is attributed to the large strain exerted on the lattice upon substitution of Cd by the much smaller Fe ion.

Cation distribution and crystal chemistry of Y3Al5−x Ga x O12 (0 ≤ x ≤ 5) garnet solid solutions

1999 ◽  
Vol 55 (3) ◽  
pp. 266-272 ◽  
Author(s):  
Akihiko Nakatsuka ◽  
Akira Yoshiasa ◽  
Takamitsu Yamanaka
Keyword(s):  
Solid Solutions ◽  
Large Deviation ◽  
Repulsive Force ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
Flux Method ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law ◽  
Cation Distributions

Five single crystals of Y3Al5−x Ga x O12 (0 ≤ x ≤ 5) garnet solid solutions with the compositions x = 0.0, 1.0, 2.0, 3.0 and 4.0 were synthesized using a flux method. The compositional dependence of the lattice constants of the garnet solid solutions shows a large deviation from Vegard's law. Investigation of the cation distributions of these garnets using single-crystal X-ray diffraction shows that Ga3+, which is larger than Al3+, preferentially occupies the tetrahedral (four-coordinate) site rather than the octahedral (six-coordinate) site. On the basis of the results obtained from structure refinements, geometric analyses of the polyhedral distortions were carried out. The results imply that the cation–cation repulsive force across the polyhedral shared edges decreases with increasing substitution of Ga3+. Moreover, the proportion of covalent bonding in the cation–oxygen bonds was estimated from the bond strength; the results indicate that the covalency of the Ga—O bond is greater than that of the Al—O bond. The peculiar cation distributions observed in the Y3Al5−x Ga x O12 garnet solid solutions are most probably caused by the strong covalency of the Ga—O bond and also simultaneously induced by the need to decrease the cation–cation repulsive force. Crystal data: cubic, Ia3¯d, Z = 8, Mo Kα, λ = 0.71069 Å; at x = 0.0 (triyttrium pentaaluminium dodecaoxide): a 0 = 12.0062 (5) Å, V = 1730.7 (2) Å3, D x = 4.56 Mg m−3, M r = 593.613, μ = 21.21 mm−1, F(000) = 2224, R = 0.029 for 294 reflections; at x = 1.0 (triyttrium tetraaluminium gallium dodecaoxide): a 0 = 12.0432 (7) Å, V = 1746.7 (3) Å3, D x = 4.84 Mg m−3, M r = 636.351, μ = 24.09 mm−1, F(000) = 2368, R = 0.022 for 124 reflections; at x = 2.0 (triyttrium trialuminium digallium dodecaoxide): a 0 = 12.0926 (9) Å, V = 1768.3 (4) Å3, D x = 5.10 Mg m−3, M r = 679.089, μ = 26.85 mm−1, F(000) = 2512, R = 0.018 for 144 reflections; at x = 3.0 (triyttrium dialuminium trigallium dodecaoxide): a 0 = 12.1552 (6) Å, V = 1795.9 (3) Å3, D x = 5.34 Mg m−3, M r = 721.827, μ = 29.43 mm−1, F(000) = 2656, R = 0.018 for 184 reflections; at x = 4.0 (triyttrium aluminium tetragallium dodecaoxide): a 0 = 12.2123 (8) Å, V = 1821.3 (4) Å3, D x = 5.58 Mg m−3, M r = 764.565, μ = 31.97 mm−1, F(000) = 2800, R = 0.014 for 159 reflections.

Time Dependence of γ/γ' Lattice Mismatch in Creep-Deformed Single Crystal Superalloy SC16 at 1173 K

2007 ◽  
Vol 539-543 ◽  
pp. 3059-3063 ◽  
Author(s):  
G. Schumacher ◽  
N. Darowski ◽  
I. Zizak ◽  
Hellmuth Klingelhöffer ◽  
W. Chen ◽  
...  
Keyword(s):  
Single Crystal ◽  
Lattice Mismatch ◽  
Lattice Misfit ◽  
Peak Position ◽  
Single Crystal Superalloy ◽  
Tensile Creep ◽  
Full Width ◽  
X Ray Diffraction ◽  
X Ray ◽  
Time Period

The profiles of 001 and 002 reflections have been measured at 1173 K as a function of time by means of X-ray diffraction (XRD) on tensile-creep deformed specimens of single crystal superalloy SC16. Decrease in line width (full width at half maximum: FWHM) by about 7 % and increase in peak position by about 3x10-4 degrees was detected after 8.5x104 s. Broadening of the 002 peak profile indicated a more negative value of the lattice misfit after the same time period. The results are discussed in the context of the anisotropic arrangement of dislocations at the γ/γ’ interfaces during creep and their rearrangement during the thermal treatment at 1173 K.

Optical and structural prorerties of InAs epilayer on graded InGaAs

2001 ◽  
Vol 696 ◽  
Author(s):  
Gu Hyun Kim ◽  
Jung Bum Choi ◽  
Joo In Lee ◽  
Se-Kyung Kang ◽  
Seung Il Ban ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Residual Strain ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Peak Position ◽  
Excitation Intensity ◽  
Total Thickness ◽  
Ingaas Layer ◽  
X Ray Diffraction ◽  
X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

Sign in / Sign up

Export Citation Format

Share Document