Tetragonal Strain in MBE GexSi1-x Films Grown on (100) Si Observed by Ion Channeling and X-Ray Diffraction

1983 ◽  
Vol 25 ◽  
Author(s):  
A. T. Fiory ◽  
L. C. Feldman ◽  
J. C. Bean ◽  
I. K. Robinson
Keyword(s):  
Molecular Beam ◽  
Critical Thickness ◽  
Ion Beam ◽  
Growth Surface ◽  
X Ray Diffraction ◽  
Strained Layers ◽  
X Ray ◽  
Ion Channeling ◽  
Pseudomorphic Growth ◽  
Beam Damage

ABSTRACTStructure of GexSi1-x alloy films grown on (100) Si by molecular beam epitaxy is analyzed by MeV He+ ion channeling and X-ray diffraction as functions of Ge concentration, film thickness and growth temperature. Critical thicknesses for pseudomorphic growth are determined for x ≤ 0.5, where coherent tetragonally-strained layers are observed. The average strain decreases approximately as the square-root of thickness when the critical thickness is exceeded. At temperatures near the threshold for islanding growth, surface roughness appears as a precursor to degradation of strained-layer epitaxy. No effect on the amount of the tetragonal strain was found in a study of ion-beam damage.

Effect of ion‐beam damage on x‐ray diffraction and Raman spectra of amorphous GeSe2

1983 ◽  
Vol 54 (4) ◽  
pp. 1792-1794 ◽  
Author(s):  
M. Marcus ◽  
R. C. Dynes ◽  
J. E. Griffiths ◽  
D. McWhan
Keyword(s):  
Raman Spectra ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Beam Damage

X-Ray Diffraction Determination of Critical Thickness of InAs and InP on GaAs Grown by Atomic Layer Molecular Beam Epitaxy

1992 ◽  
Vol 263 ◽  
Author(s):  
A. Mazuelas ◽  
L. Gonzalez ◽  
L. Tapfer ◽  
F. Briones
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Critical Thickness ◽  
Atomic Layer ◽  
Dynamical Theory ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strained Layer ◽  
Diffraction Determination ◽  
Cap Layer

ABSTRACTTwo series of samples consisting in a strained layer of InAs (InP) of different thickness, InAs N monolayers (ML) with N=1,2,3, and 4, and, InP M ML with M=2,3,4,5,6 and 7, covered by a GaAs cap layer of 200 nm were grown by Atomic Layer Molecular Beam Epitaxy (ALMBE).The samples have been characterized by X-ray diffraction in order to measure the critical thickness of InAs and InP on GaAs.Computer simulation using dynamical theory of X-ray diffraction is used to fit the experimental patterns. In this way we determine the composition, thickness, and strain both in the strained layer of InAs or InP and in the cap layer of GaAs.A disagreement between simulated and experimental curves is reached at a thickness where the beginning of relaxation takes place (i.e. critical thickness). We have found that the critical thickness of InAs on GaAs(001) is 2.3 ML (0.75 nm) and the critical thickness of InP on GaAs(001) is 5.6–5.7 ML (1.71-1.74 nm), both grown by ALMBE.

On the Critical Layer Thickness of Strained-Layer Heteroepitaxial CoSi2 Films on 〈111〉Si

1987 ◽  
Vol 91 ◽  
Author(s):  
David N. Jamieson ◽  
G. Bai ◽  
Y. C. Kao ◽  
C. W. Nieh ◽  
M-A. Nicolet ◽  
...  
Keyword(s):  
Critical Thickness ◽  
Ion Beam ◽  
Thin Layers ◽  
Maximum Magnitude ◽  
Critical Layer Thickness ◽  
Double Crystal ◽  
Strained Layers ◽  
X Ray ◽  
Planar Growth

ABSTRACTThe technique of Double Crystal X-Ray Diffractometry (DXD) and ion beam channeling are applied to investigate, as a function of thickness, the average perpendicular strain and crystal quality of CoSi2 layers grown by MBE on 〈111〉Si. The results show that thin layers (from 20 to 30 nm) are partially relaxed but with a strain greater than that expected for a free CoSi2 lattice. For layers thicker than 30nm the magnitude of the CoSi2 strain incrgases to 1.7%, somewhat less than the maximum magnitude strain expected for coherent growth (2.1%). For layers thicker than 50 nm, the perpendicular strain relaxes very slowly, with the strain at 225 nm only 5% less than that at 50nm. It was concluded that a coherent epitaxial layer does not form initially and the relaxation of the strained layers is not consistent with a planar growth mechanism of the CoSi2 epilayers. Therefore the concept of a critical thickness, below which the epilayers are strained and above which the epilayers are relaxed, cannot be applied to our CoSi2/Si system.

InGaAs/GaAs Quantum Well Structures Grown by Migration-Enhanced Epitaxy

1992 ◽  
Vol 263 ◽  
Author(s):  
J.E. Wu ◽  
H.M. Yoo ◽  
T.G. Stoebe
Keyword(s):  
Growth Rate ◽  
Quantum Well ◽  
Critical Thickness ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Strained Layers ◽  
Quantum Well Structures ◽  
X Ray ◽  
Migration Enhanced Epitaxy ◽  
And Migration

ABSTRACTGaAs/In.2Ga.8As/GaAs quantum well structures containing InGaAs layers of thickness over and under the critical thickness (hc) were studied, as grown by both conventional molecular beam epitaxy (C-MBE) and migration-enhanced epitaxy (MEE) techniques. A 6.0 monolayer per cycle (ML/cyc) growth rate, in contrast to a one or less-than-one ML/cyc growth rate used in a conventional MEE process, was used to grow In.2Ga.8As layers over hc. As-grown samples were characterized via photoluminescence, X-ray diffraction, and transmission electron microscopy (TEM). The 6.0 ML/cyc MEE-grown layers over hc show superior optical quality to MBE-grown layers with the same thickness. Both X-ray diffraction and TEM microstructure results indicate that the 6.0 ML/cyc MEE-grown In.2Ga.8As layers are still strained layers while those grown by conventional MBE method are not. The 6.0 ML/cyc MEE process seems to be advantageous for growing InGaAs layers over the critical thickness.

Structural Properties of Single Crystal Rare-Earth Thin Films Y and Gd Grown by Molecular Beam Epitaxy

1984 ◽  
Vol 37 ◽  
Author(s):  
J. Kwo ◽  
D. B. McWhan ◽  
M. Hong ◽  
E. M. Gyorgy ◽  
L. C. Feldman ◽  
...  
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Molecular Beam ◽  
Rare Earth Metals ◽  
Earth Metal ◽  
Metal Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ion Channeling

AbstractBy means of metal MBE technique with in-situ RHEED characterization, high-quality single crystal rare earth metal films of yttrium and gadolinium were grown as a necessary requirement for studying Gd/Y superlattices. The key step of this successful growth is the employment of the single-crystal Nb film as a buffer layer to eliminate the interaction of rare earth metals with most substrates. Structural analyses by X-ray diffraction and ion channeling show that these crystals exhibit not only complete texture of [00.1], but also narrow rocking curves both perpendicular (00.2) and parallel (10.0) to the film.

Ion Beam Synthesis and Optical Properties of Zn and Zno Nanocrystals in Sio2 and Caf2 Substrates

2003 ◽  
Vol 777 ◽  
Author(s):  
Y.C. Liu ◽  
R. Mu ◽  
H.Y. Xu ◽  
Y.M. Lu ◽  
D.Z. Shen ◽  
...  
Keyword(s):  
Ion Beam ◽  
Green Emission ◽  
Zinc Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Zno Nanocrystals ◽  
Nanocrystal Formation ◽  
Beam Damage ◽  
Zno Nanocrystal

AbstractIon implantation was used to inject zinc ions into crystalline CaF2 and amorphous SiO2 substrates. Zn or ZnO nanoparticles were formed after annealing in a reducing (4% H2 + 96%Ar) or an oxidizing (10%O2 + 90% Ar ) atmosphere, respectively. When the sample was annealed in a reducing atmosphere, the absorption band at ∼ 5.3 eV for zinc implanted into SiO2 was attributed to zinc metal colloids. The absorption peak observed in the 4.3 – 4.7 eV region was due to the formation of ZnO nanocrystals, after the sample was annealed in an oxidizing environment. Both X-ray diffraction (XRD) and X-ray photospectroscopy (XPS) were used to confirm ZnO nanocrystal formation. For zinc implanted into CaF2, the as-formed ZnO nanocrystals were aligned with their [002] axes parallel to the [111] axis of the CaF2. Photoluminescence (PL) spectra showed UV and green emission from the zinc-implanted silica samples annealed under an oxygen atmosphere; however, no green emission was observed for ZnO formed in a CaF2 substrate. An additional emission was observed at ∼ 420 nm which might be due to F centers in CaF2 created by ion beam damage.

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.

Ion Beam Synthesis of Buried CoSi2 Layers in SiGe Alloys

1992 ◽  
Vol 279 ◽  
Author(s):  
R. Jebasinski ◽  
S. Mantl ◽  
Chr. Dieker ◽  
H. Dederichs ◽  
L. Vescan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Implantation ◽  
Single Crystal ◽  
Rapid Thermal Annealing ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ion Channeling ◽  
Transmission Electron

ABSTRACTSynthesis of buried, epitaxial CoSi2 layers in Si1−xGex alloys (x =0.48 and x = 0.09) by 100 and 150 keV Co+ ion implantation and subsequent rapid thermal annealing was studied by X-Ray diffraction, Rutherford backscattering spectroscopy, He ion channeling, Auger Eectron Spectroscopy and Transmission Electron Microscopy. Buried single-crystal CoSi2 layers in the Si0.91Ge0.09 alloy containing ≈ 1 at% Ge were formed. The suicide formation causes an outdiffusion of Ge leading to an increase in the Ge concentration of the adjacent SiGe layers. In contrast, in the Si0.52Ge0.48 alloy no buried suicide layers could be produced.

Interfacial properties of GaSb/InAs superlattices

1993 ◽  
Vol 51 ◽  
pp. 826-827
Author(s):  
M. E. Twigg ◽  
B. R. Bennett ◽  
J. R. Waterman ◽  
J. L. Davis ◽  
B. V. Shanabrook ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Molecular Beam ◽  
Infrared Detector ◽  
Interfacial Properties ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Short Period ◽  
High Optical Absorption

Recently, the GaSb/InAs superlattice system has received renewed attention. The interest stems from a model demonstrating that short period Ga1-xInxSb/InAs superlattices will have both a band gap less than 100 meV and high optical absorption coefficients, principal requirements for infrared detector applications. Because this superlattice system contains two species of cations and anions, it is possible to prepare either InSb-like or GaAs-like interfaces. As such, the system presents a unique opportunity to examine interfacial properties.We used molecular beam epitaxy (MBE) to prepare an extensive set of GaSb/InAs superlattices grown on an GaSb buffer, which, in turn had been grown on a (100) GaAs substrate. Through appropriate shutter sequences, the interfaces were directed to assume either an InSb-like or GaAs-like character. These superlattices were then studied with a variety of ex-situ probes such as x-ray diffraction and Raman spectroscopy. These probes confirmed that, indeed, predominantly InSb-like and GaAs-like interfaces had been achieved.

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.

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