Characterisation of Thin Lattice Mismatched Heteroepitaxial Layers by XRD

1991 ◽  
Vol 240 ◽  
Author(s):  
Mary A. G. Halliwell
Keyword(s):  
Layer Thickness ◽  
Critical Thickness ◽  
Growth Conditions ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Small Factor ◽  
Highly Strained ◽  
Heteroepitaxial Layers

ABSTRACTMany advanced III - V devices require highly strained heteroepitaxial layers less than 25 nm in thickness, with tight specifications on both the layer thickness and composition. In many cases the layers required are close to the critical thickness.The growth conditions for these thin layers are often extrapolated from established conditions for thicker layers. This method can result in layers which have the incorrect thickness and composition because of the transients which occur as growth commences. To minimise this problem it is desirable to establish growth conditions for layers which are as close to device requirements as possible. X-ray diffraction is capable of measuring layer thicknesses and compositions non-destructively. The minimum measurable layer thickness is usually within a small factor (typically 0.5 to 5 times) of device requirements.A single x-ray rocking curve is required to determine the thickness and composition of an unrelaxed (strained) layer. At least two rocking curves are required when relaxation is present. This paper discusses the appropriate choice of measurement conditions for a given sample.

High Resolution X-ray Diffraction for the Characterization of Semiconducting Materials

1989 ◽  
Vol 33 ◽  
pp. 1-11 ◽  
Author(s):  
B. K. Tanner
Keyword(s):  
Bragg Peak ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Semiconducting Materials ◽  
Multiple Reflections ◽  
X Ray ◽  
Analyzer Crystal ◽  
Glancing Angle ◽  
Heteroepitaxial Layers

AbstractUse of a reference crystal to condition the beam in the double-axis diffractometer permits the Bragg peak width to be reduced to the correlation of the two crystal reflecting ranges. Some recent applications of double axis diffractometry to the study of heteroepitaxial layers are discussed. The advantages of multiple reflections for beam conditioning and the four reflection DuMond monochromator are examined. Glancing incidence and exit diffractometry permits the study of very thin layers, down to a few tens of nanometres in thickness and both synchrotron radiation and skew reflections can be used to tune the glancing angle close to the critical angle. Recent applications of triple-axis diffraction, where an analyzer crystal is used after the specimen, to the study of very thin single epitaxial layers and multiquantum well structures are reviewed.

Orientation Dependence of CdTe/Si Grown by MBE

1995 ◽  
Vol 399 ◽  
Author(s):  
L. A. Almeida ◽  
Y. P. Chen ◽  
J. P. Faurie ◽  
David J. Smith ◽  
S.-C. Y. Tsen ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Orientation Dependence ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
Substrate Preparation ◽  
Double Crystal ◽  
Interface Quality ◽  
Rocking Curve ◽  
X Ray ◽  
Transmission Electron

ABSTRACTIn this study CdTe (111)B was grown by molecular beam epitaxy on vicinal Si(001) substrates, with a variety of substrate tilt angles (θ), and tilt directions (φ) relative to [110]. Layer quality, and content of double-domain and microtwin defects were evaluated by double crystal rocking curve (DCRC) full width at half maximum (FWHM) and x-ray diffraction, respectively. Transmission electron microscopy (TEM) was used to study interface quality and the nature of structural defects as a function of epilayer thickness. In the present investigation, substrate preparation and growth conditions, particularly initiation conditions, are correlated with Si (001) tilt. It has been found that oxide desorption processes can depend strongly on θ, especially for larger values of θ (> 4°). Currently, we routinely produce single domain, twin-free CdTe(111)B epilayers on vicinal Si (001) substrates.

Hrxrd Study of the Strain Properties of MBE-Grown ZnSe and ZnSTe on GaAs

1994 ◽  
Vol 340 ◽  
Author(s):  
I.K. Sou ◽  
S.M. Mou ◽  
Y.W. Chan ◽  
G.C. Xu ◽  
G.K.L. Wong
Keyword(s):  
Layer Thickness ◽  
Gaas Substrate ◽  
Critical Thickness ◽  
Dynamical Theory ◽  
X Ray Diffraction ◽  
Strained Layers ◽  
X Ray ◽  
Znse Layer ◽  
Vegard’S Law ◽  
First Time

ABSTRACTWe have studied the structural properties of MBE-grown ZnSe/GaAs and ZnSTe/GaAs heterostructures using high resolution X-ray diffraction (HRXRD). The transition from pseudomorphic to partially and then fully relaxed strained layers is observed as a function of ZnSe layer thickness. The critical thickness for the on-set of strained relaxation for ZnSe on GaAs(001) is determined to be between 1600 and 1850 Å. Using a simulation program based on the dynamical theory, the poisson's ratio of ZnSe is accurately determined to be v=0.380±0.002. A set of ZnSl-xTex epilayers with 0 ≤ × ≤ 1 was grown on GaAs by MBE for the first time. A linear dependence of the lattice constant upon Te composition is found, which agrees well with the Vegard's Law. The characteristic behaviors of inclination between the layer and substrate planes as a function of layer thickness has been studied on both ZnSe/GaAs and ZnSTe/GaAs systems. The atomic planes of both ZnSe and ZnSTe layers are observed to tilt from those of the GaAs substrate.

Grain-Oriented Lithium Niobate Thin-Layers Prepared by Sol-Gel Methods

1990 ◽  
Vol 200 ◽  
Author(s):  
Daniel S. Hagberg ◽  
D. A. Payne
Keyword(s):  
Lithium Niobate ◽  
Sol Gel ◽  
Preferred Orientation ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Polycrystalline Platinum ◽  
Dielectric Data

ABSTRACTThin-layers of lithium niobate were deposited on polycrystalline platinum and (001) sapphire. Preferred orientation was observed by x-ray diffraction measurements, and confirmed by x-ray rocking curve studies. The orientation was [006] LiNbO3 with [111] Pt and [001] Al2O3. Dielectric data are reported for grain oriented LiNbO3 as a function of frequency for layer thicknesses from 0.15 to 0.70 μm.

Structural Characterization of Bulk AlN Single Crystals Grown from Self-Seeding and Seeding by SiC Substrates

2006 ◽  
Vol 527-529 ◽  
pp. 1521-1524 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Rafael Dalmau ◽  
Michael Dudley ◽  
Raoul Schlesser ◽  
Dejin Zhuang ◽  
...  
Keyword(s):  
Growth Conditions ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
Free Standing ◽  
X Ray ◽  
Highly Strained ◽  
Defect Densities ◽  
High Defect Densities

Using a combination of synchrotron white beam x-ray topography (SWBXT) and high resolution x-ray diffraction (HRXRD), the structural quality of AlN crystals grown by various sublimation-based techniques have been non-destructively analyzed. Spontaneously nucleated AlN crystals are characterized by very low defect densities but their size is small. Self-seeding results in nucleation of multiple grains of different orientations, a few of which are of good quality while most are highly strained. Using readily available commercial 4H and 6H-SiC substrates, several growth runs have been carried out using different growth conditions to obtain thick AlN layers, either attached to the seed or free-standing. While attached layers are typically cracked and highly strained, crack-free free-standing layers can be obtained by delamination or SiC decomposition. X-ray characterization reveals these crystals have good purity but moderately high defect densities.

X-ray diffraction evidence for transient composition effects in MOVPE multilayer growth for Ga1−x Al x As alloys

1987 ◽  
Vol 20 (3) ◽  
pp. 230-234 ◽  
Author(s):  
S. Bensoussan ◽  
C. Malgrange ◽  
M. Sauvage-Simkin ◽  
K. N'Guessan ◽  
P. Gibart
Keyword(s):  
Vapour Phase ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Vapour Phase Epitaxy ◽  
Rocking Curve ◽  
X Ray ◽  
Layer Stacking ◽  
Metal Organic ◽  
Organic Vapour ◽  
Ray Methods

X-ray rocking-curve analysis is applied to the detection of artifacts in multilayer epitactic growth of III–V ternary compounds by metal–organic vapour-phase epitaxy (MOVPE). Transient spikes in the composition result in unwanted additional thin layers whose presence disturbs the interference pattern expected from the designed heterostructures, thus modifying the oscillating part of the reflection profile. X-ray methods and secondary-ion mass spectroscopy (SIMS) lead to descriptions of the actual layer stacking in good agreement with each other.

X-ray diffraction properties of curved crystal diffractors

1992 ◽  
Vol 50 (2) ◽  
pp. 1734-1735
Author(s):  
W. Z. Chang ◽  
D. B. Wittry
Keyword(s):  
Diffraction Theory ◽  
X Rays ◽  
Diffraction Image ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Bent Crystal ◽  
Diffraction Geometry ◽  
Crystal Parameter ◽  
Quantitative Procedure

Since Du Mond and Kirkpatrick first discussed the principle of a bent crystal spectrograph in 1930, curved single crystals have been widely utilized as spectrometric monochromators as well as diffractors for focusing x rays diverging from a point. Curved crystal diffraction theory predicts that the diffraction parameters - the rocking curve width w, and the peak reflection coefficient r of curved crystals will certainly deviate from those of their flat form. Due to a lack of curved crystal parameter data in current literature and the need for optimizing the choice of diffraction geometry and crystal materials for various applications, we have continued the investigation of our technique presented at the last conference. In the present abstract, we describe a more rigorous and quantitative procedure for measuring the parameters of curved crystals.The diffraction image of a singly bent crystal under study can be obtained by using the Johann geometry with an x-ray point source.

scholarly journals Irregular Electrodeposition of Cu-Sn Alloy Coatings in [EMIM]Cl Outside the Glove Box with Large Layer Thickness

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 310
Author(s):  
Lars Lehmann ◽  
Dominik Höhlich ◽  
Thomas Mehner ◽  
Thomas Lampke
Keyword(s):  
Layer Thickness ◽  
Alloy System ◽  
Liquid Solution ◽  
Complexing Agents ◽  
X Ray Diffraction ◽  
X Ray ◽  
Argon Stream ◽  
Ionic Liquid Solution ◽  
The Relationship ◽  
Layer Composition

Thick Cu−Sn alloy layers were produced in an [EMIM]Cl ionic-liquid solution from CuCl2 and SnCl2 in different ratios. All work, including the electrodeposition, took place outside the glovebox with a continuous argon stream over the electrolyte at 95 °C. The layer composition and layer thickness can be adjusted by the variation of the metal-salts content in the electrolyte. A layer with a thickness of up to 15 µm and a copper content of up to ωCu = 0.86 was obtained. The phase composition was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). Furthermore, it was found that the relationship between the alloy composition and the concentration of the ions in the electrolyte is described as an irregular alloy system as according to Brenner. Brenner described such systems only for aqueous electrolytes containing complexing agents such as cyanide. In this work, it was confirmed that irregular alloy depositions also occur in [EMIM]Cl.

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