Effects of thermal processing on (SimGen)p superlattices

1991 ◽  
Vol 69 (3-4) ◽  
pp. 241-245 ◽  
Author(s):  
R. Pascual ◽  
S. Saimoto ◽  
J. M. Baribeau
Keyword(s):  
Structural Changes ◽  
Strain Relaxation ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
Exponential Decay Rate ◽  
Superlattice Peak ◽  
Short Period ◽  
Short Period Superlattices ◽  
Short Annealing

In this work we report an X-ray diffraction study of thermally induced interdiffusion and strain relaxation in molecular beam epitaxy grown (SimGen)p short-period superlattices. Both rapid and furnace thermal annealings in the range 500–700 °C were used to generate structural changes in the various samples. Strain relaxation was studied by measuring the shift of (400) superlattice peaks on annealing. About half of the strain was relieved in the first few minutes of annealing. The remaining strain was relieved at a much lower rate and residual strain persisted even after several hours of heating. Also, the decay of the first order (000) superlattice peak was monitored as a function of annealing time. An initial rapid nonexponential decrease in peak intensity was observed, coincident with the sudden strain relaxation found at short annealing times. A slower, exponential decay rate was observed at longer times, so that a wavelength-dependent interdiffusion coefficient Dλ could be calculated. The variation of Dλ with the superlattice period and the effect of different substrates and buffer layers was studied. Diffusion was faster in structures alternating thin Si and thick Ge layers suggesting that migration of Si into Ge is the dominant diffusion process.

scholarly journals High Resolution X-Ray Diffraction Investigations of Si/SiGe Quantum Well Structures and Si/Ge Short-Period Superlattices

1993 ◽  
Vol 84 (3) ◽  
pp. 475-489
Author(s):  
G. Bauer ◽  
E. Koppensteiner ◽  
P. Hamberger ◽  
J. Nützel ◽  
G. Abstreiter ◽  
...  
Keyword(s):  
High Resolution ◽  
Quantum Well ◽  
X Ray Diffraction ◽  
Quantum Well Structures ◽  
X Ray ◽  
Short Period ◽  
Short Period Superlattices

Thermally induced strain relaxation in SiGe/Si heterostructures with low-temperature buffer layers

2005 ◽  
Vol 2 (6) ◽  
pp. 1938-1942 ◽  
Author(s):  
V. I. Vdovin ◽  
T. G. Yugova ◽  
M. M. Rzaev ◽  
F. Schäffler ◽  
M.G. Mil'vidskii
Keyword(s):  
Low Temperature ◽  
Strain Relaxation ◽  
Buffer Layers ◽  
Thermally Induced

Multiple dielectric anomalies in xBiLaO3–(1 − x)PbTiO3 piezoelectrics

2008 ◽  
Vol 23 (2) ◽  
pp. 565-569 ◽  
Author(s):  
Runrun Duan ◽  
Michael S. Haluska ◽  
Robert F. Speyer
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Excellent Agreement ◽  
Structural Changes ◽  
Dielectric Anomaly ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Thermally Induced ◽  
X Ray ◽  
Higher Temperature

Compositions of xBiLaO3–(1 − x) PbTiO3 over the range 0 ≤ x ≤ 0.225 were calcined and sintered. The dielectric constant with temperature and differential scanning calorimetry measurements were in excellent agreement with respect to Curie-like tetragonal to cubic transformations starting at 495 °C for pure PbTiO3, shifting to lower temperatures with increasing x. For compositions of x ≥ 0.05, a second higher-temperature (∼600 °C) endotherm, and matching dielectric anomaly, were consistently observed, for which there were no structural changes indicated by hot-stage x-ray diffraction. This transformation was speculated to be based on a thermally induced desegregation of B-site cations.

Macro-and Microstrain Relaxation in Annealed Ag Films During Ageing at Room Temperature

1997 ◽  
Vol 505 ◽  
Author(s):  
R. C. Currie ◽  
R. Delhez ◽  
E. J. Mitiemeijer
Keyword(s):  
Room Temperature ◽  
Strain Relaxation ◽  
Diffraction Line ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Diffraction Line Profile ◽  
The Matrix ◽  
Profile Position

ABSTRACTThe relaxation of thermally induced strain in 500 nm thick polycrystalline Ag layers electron-beam deposited onto Si wafers was traced during ageing at room temperature. The layers consisted predominantly of matrix crystallites with {111} planes parallel to the surface and twin crystallites with {51 l} planes parallel to the surface. The macrostrain in the plane of the layer was determined from the X-ray diffraction line-profile position and the microstrain from the diffraction-line broadening. The residual macrostress relaxed from 160 MPa to 30 MPa in the matrix crystallites and from 170 MPa to 50 MPa in the twin crystallites. Simultaneously with the decrease in macrostress the microstrain decreases significantly for both texture fractions. The strain relaxation behaviour is governed by movement and subsequent annihilation of defects in the layer.

Interrelation between Strain Relaxation and InxAl1-xAs Compositional Graded Step Buffer Layers on GaAs Substrate Grown by Molecular Beam Epitaxy

2007 ◽  
Vol 124-126 ◽  
pp. 127-130
Author(s):  
Sook Hyun Hwang ◽  
Yu Mi Park ◽  
Hoon Ha Jeon ◽  
Kyung Seok Noh ◽  
Jae Kyu Kim ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Gaas Substrate ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Compositional Gradient ◽  
Transmission Electron ◽  
Two Samples ◽  
Compositional Gradients

We have grown delta-doped In0.5Ga0.5As /In0.5Al0.5As heterostructures on GaAs substrate applying with InxAl1-xAs compositional graded-step buffers, called metamorphic structures, grown by molecular beam epitaxy. Three types of buffer layers with different compositional gradients and thicknesses have designed to investigate the influence of the strain relaxation process. We characterized the samples by using transmission electron microscopy, triple-axis X-ray diffraction and Hall measurement. Two samples with different compositional gradient show almost same results in electrical properties. On the other hand, it is found that samples with different step thicknesses had shown the large differences in epilayer tilt and mosaic spread in the step-graded buffers. These results indicate that there exists an interrelation between the strain-relaxed buffer and 2DEG transport properties.

Double Periodicity Formation in EuTe/PbTe Superlattices

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Shima ◽  
L. Salamanca-Riba ◽  
G. Springholz ◽  
G. Bauer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices

ABSTRACTMolecular beam epitaxy was used to grow EuTe(x)/PbTe(y) short period superlattices with x=1-4 EuTe(111) monolayers alternating with y≈3x PbTe monolayers. The superlattices were characterized by transmission electron microscopy and high resolution x-ray diffraction. Regions with double periodicity were observed coexisting with areas of nominal periodicity. The sample with x=3.5 and y=9, for example, contains regions with double periodicity of x=7 and y=17. X-ray diffraction measurements confirm the formation of the double periodicity in these samples by the appearance of weak satellites in between the satellites of the nominal periodicity. The double periodicity in the superlattice is believed to result from interdiffusion during the growth. A model for this process is presented.

Characterization of ultrathin Ge epilayers on (100) Si

1991 ◽  
Vol 69 (3-4) ◽  
pp. 246-254 ◽  
Author(s):  
J. -M. Baribeau ◽  
D. J. Lockwood ◽  
T. E. Jackman ◽  
P. Aebi ◽  
T. Tyliszczak ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Three Dimensional ◽  
Raman Scattering Spectroscopy ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Short Period Superlattices ◽  
Direct Band ◽  
X Ray Absorption

The understanding of the epitaxy of pure Ge layers on Si is an important step towards the synthesis of SimGen (m, n < 10 monolayers) short-period superlattices. The possibility of a direct band-gap character makes these structures extremely attractive. We have grown thin buried Gen ([Formula: see text] monolayers) films on (100) Si by molecular beam epitaxy and studied their structural properties by a variety of techniques including Raman scattering spectroscopy, glancing incidence X-ray reflection, Rutherford backscattering, transmission electron microscopy, and extended X-ray absorption fine structure analysis. All these techniques allowed detection of the thin Ge layers and provided information about the thickness, morphology, strain distribution, and interface sharpness of these heterostructures. The Ge„ films with [Formula: see text] had a two-dimensional nature and showed no sign of strain relaxation. Intermixing at the Si–Ge interfaces was present in all these films and estimated to be not more than two monolayers. This smearing at the interfaces may have contributed to the maintenance of that pseudomorphicity. A thicker Ge layer (n = 12) showed evidence of strain relaxation and clustering in three-dimensional islands.

Optical and Structural Characterization of Nanocrystalline Silicon Superlattices: Toward Nanoscale Silicon Metrology

2000 ◽  
Vol 638 ◽  
Author(s):  
Stefan Zollner ◽  
Atul Konkar ◽  
Ran Liu ◽  
Himansu Yapa ◽  
Patricia F. Dryer ◽  
...  
Keyword(s):  
Finite Size ◽  
Optical Excitation ◽  
Nanocrystalline Silicon ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Short Period ◽  
Structural Transmission ◽  
Short Period Superlattices

AbstractShort-period superlattices consisting of nanocrystalline Si wells and amorphous SiO2 barriers were analyzed using various structural (transmission electron microscopy, atomic force microscopy, and x-ray diffraction) and optical (Raman scattering and spectroscopic ellipsometry) characterization techniques. We observe parallel layers containing polycrystalline Si wells, primarily with <111> orientation, and an interesting surface morphology due to sputtering damage. Raman spectra show a redshift and broadening due to finite-size effects. The ellipsometry data can be described using the effective medium approximation (since the superlattice period is much shorter than the wavelength of the optical excitation) or a superlattice approach based on the Fresnel equations with a polycrystalline Si dielectric function.

Strain Relaxation Process of(InAs)m(GaAs)nStrained Short-Period Superlattices Grown by Molecular Beam Epitaxy

1994 ◽  
Vol 33 (Part 1, No. 10) ◽  
pp. 5617-5622 ◽  
Author(s):  
Takahiro Kawai ◽  
Hiroo Yonezu ◽  
Daishiro Saito ◽  
Mikihiro Yokozeki ◽  
Kangsa Pak
Keyword(s):  
Molecular Beam Epitaxy ◽  
Relaxation Process ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Short Period ◽  
Short Period Superlattices
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