Strain Shift Coefficients for Phonons in Si-Ge Heterostructures

1991 ◽  
Vol 239 ◽  
Author(s):  
J.-M. Baribeau ◽  
D. J. Lockwood
Keyword(s):  
Molecular Beam ◽  
Composition Dependence ◽  
Vibration Mode ◽  
Phonon Frequency ◽  
Longitudinal Optical ◽  
Stress Factor ◽  
Double Crystal ◽  
Raman Scattering Spectroscopy ◽  
X Ray ◽  
Shift Coefficient

ABSTRACTStrain shift coefficient measurements for longitudinal optical phonons in molecular beam epitaxy grown metastable pseudomorphic Si1−xGex layers on (100) Si (0 < x < 0.35) and Ge (0.80 < x < 1) are reported. Strain in partially relaxed annealed specimens was obtained by double-crystal x-ray diffractometry and the corresponding strain phonon shift was measured by Raman scattering spectroscopy. For epilayers grown on Si it was found that the epilayer Si-Si phonon frequency varies linearly with strain. The magnitude of the strain shift coefficient b however showed a small composition dependence varying from b ≈ -700 cm-1 at x = 0 to b ≈ -950 cm-1 at x = 0.35, corresponding to a stress factor τ = 0.40 + 0.57x: + 0.13x2 cm-1/kbar. For the Ge-Ge vibration mode in epilayers grown on Ge, b decreased from ∼-425 cm-1 at x = 1 to ∼-500 cm-1 at x = 0.8, corresponding to a stress factor τ ≈ 0.52 – 0.14x - 0.08x2 cm-1/kbar.

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.

Anisotropic Lattice Relaxation and its Mechanism of ZnSe Epilayer Grown on (001) GaAs Substrate by Molecular Beam Epitaxy

1995 ◽  
Vol 399 ◽  
Author(s):  
C.S. Kim ◽  
S.K. Noh ◽  
H.J. Lee ◽  
Y.K. Cho ◽  
Y.I. Kim ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Gaas Substrate ◽  
Molecular Beam ◽  
Rotation Angle ◽  
Lattice Relaxation ◽  
High Dislocation Density ◽  
Sinusoidal Oscillation ◽  
Double Crystal ◽  
X Ray ◽  
Anisotropic Lattice

ABSTRACTWe have investigated anisotropic lattice relaxation and its mechanism of ZnSe epitaxial layer grown on (001) GaAs substrate by MBE. Double-crystal X-ray rocking curves for (004), {115} and {404} reflections were measured as a function of the azimuthal rotation angle of the sample. We observed the sinusoidal oscillation of the FWHM of the epilayer peak for (004) reflections due to the asymmetric dislocation density along two orthogonal <110> directions, and the direction of the maximum FWHM corresponding to high dislocation density is along [110]. In addition, the strain along [110] is smaller than that along [1-10], indicating that the layer suffered anisotropic lattice relaxation. The direction of larger relaxation([l-10]) is not consistent with that of high dislocation density([110]). The results suggest that the asymmetry in dislocation density is not responsible for the anisotropic relaxation of the ZnSe epilayer.

A Study on the Strain and Microstructure in SiGe Film Grown on Si(001) Substrate by MBE

1994 ◽  
Vol 356 ◽  
Author(s):  
Kyoung-Ik Cho ◽  
Sahn Nahm ◽  
Sang-Gi Kim ◽  
Seung-Chang Lee ◽  
Kyung-Soo Kim ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Large Strain ◽  
Strain Relaxation ◽  
Stacking Faults ◽  
Double Crystal ◽  
Crystalline Layer ◽  
X Ray ◽  
Transmission Electron ◽  
Plain Strain

AbstractSi/Si0.8Ge0.2/Si(001) structures were grown at various growth temperatures (250 ∼ 760 °C) using molecular beam epitaxy, and the variation of strain and microstructure of the film was investigated using double crystal X-ray diffractometry and transmission electron microscopy. SiGe films with good single crystallinity were obtained at the growth temperatures of 440 ∼ 600 °C. For the samples grown below 350 °C, an amorphous SiGe film was developed over the SiGe single crystalline layer with a jagged amorphous/crystalline (a/c) interface, and many defects such as stacking faults and microtwins were formed below the a/c interface. Dislocations were developed through out the films for the samples grown above 680 °C. In addition, for the samples grown below 680 °C, the amount of in-plane strain of the SiGe film was found to be about − 8×l0−3 without strain relaxation. However, the SiGe films grown at 760 °C have small in-plain strain of − 4×l0−3 and large strain relaxation of 50%.

Optical and X-Ray Diffraction Characterization of MBE-Grown InGaAs, InAlAs and InGaAIAs on InP

1994 ◽  
Vol 340 ◽  
Author(s):  
Z. C. Feng ◽  
S. J. Chua ◽  
A. Raman ◽  
N.N. Lim
Keyword(s):  
Optical Properties ◽  
Fourier Transform ◽  
Molecular Beam ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Lattice Matched ◽  
Comprehensive Characterization

ABSTRACTA variety of Inl-xGaxAs, Inl-yAlyAs and Inl-x-yGaxAlyAs films have been grown on InP by molecular beam epitaxy. A comprehensive characterization was performed using Raman scattering, photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy and double crystal X-ray diffraction on these ternary and quaternary heterostructures with different compositions and growth conditions. The lattice matched and mismatched structures are studied. Our analyses show that the interface mismatch exerts an important influence on the optical properties of these heterostructures, and conversely that Raman, PL and FTIR can be used to probe the interface mismatch nondestructively.

Thickness Measurement of Epitaxical Thin Films by X-ray Diffraction Method

1988 ◽  
Vol 32 ◽  
pp. 279-284
Author(s):  
J. Chaudhuri ◽  
S. Shah ◽  
J.P. Harbison
Keyword(s):  
Thin Films ◽  
Molecular Beam ◽  
Electronic Materials ◽  
Diffraction Method ◽  
Thickness Measurement ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Kinematical Theory ◽  
Double Crystal Diffractometer

AbstractA method was described for determining the thickness of epitaxical thin films common to electronic materials. The equations were developed based on the kinematical theory of X-ray diffraction and effects of both primary and secondary extinctions were considered. As an example of the applications of this method, thickness measurement of AlGaAs thin films on GaAs was demonstrated. These films were grown by molecular beam epitaxy. The integrated reflected intensities from the film and the substrate were obtained by the X-ray double crystal diffractometer. An excellent agreement was obtained between the results from X-ray measurements and RHEED oscillation data.

Interface Quality and Interdiffusion in Si-Ge Heterostructures

1993 ◽  
Vol 312 ◽  
Author(s):  
J.-M. Baribeau ◽  
D. J. Lockwood ◽  
G. C. Aers ◽  
M. W. C. Dharma-Wardana
Keyword(s):  
Raman Scattering ◽  
Composition Dependence ◽  
Isothermal Annealing ◽  
Atomic Displacement ◽  
Strong Decay ◽  
Optical Mode ◽  
Interface Quality ◽  
Raman Scattering Spectroscopy ◽  
X Ray ◽  
Short Period

AbstractThe evolution of interfaces of short-period (SimGen)p superlattices upon annealing has been studied by x-ray reflectometry and Raman scattering spectroscopy. Isothermal annealing treatments at 700° C resulted in a significant material redistribution as evidenced by a strong decay of the superlattice x-ray satellites and by the decay of longitudinal acoustic modes and changes in the optical mode intensity ratios in Raman scattering. Interdiffusion was more pronounced in superlattices of short periodicity. This may possibly be explained by the strong composition dependence of the diffusivity of Ge atoms in Sil-xGex alloys and the degree of preexisting interfacial mixing. This composition dependence of the diffusion may favor atomic displacement parallel to the interfaces leading to an initial smoothing of the interfaces

Vertical-Cavity Optoelectronic Structures: CAD, Growth, and Structural Characterization

1992 ◽  
Vol 281 ◽  
Author(s):  
D. H. Christensen ◽  
S. M. Crochiere ◽  
J. G. Pellegrino ◽  
R. S. Rai ◽  
C. A. Parsons ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Computer Aided Design ◽  
Molecular Beam ◽  
Alloy Composition ◽  
Double Crystal ◽  
X Ray ◽  
Transmission Electron ◽  
Random Alloys ◽  
Aided Design ◽  
Vertical Cavity

ABSTRACTSimulations of reflectance spectra and electric field distributions for vertical-cavity structures were used in the computer aided design of epitaxial mirrors and lasers. The binary GaAs/AlAs superlattice alloys and AlxGa1−xAs random alloys that compose these structures were grown by molecular beam epitaxy. Photoluminescence, photoreflectance, reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, and double crystal x-ray diffractometry were applied to characterize cavity and Bragg mirror layer thicknesses and alloy composition.

Molecular Beam Epitaxy Study of InAs/GaSb Heteroepitaxy on The (111)A and (111)B Orientations

1992 ◽  
Vol 263 ◽  
Author(s):  
J. A. Dura ◽  
J. T. Zborowski ◽  
T. D. Golding
Keyword(s):  
Molecular Beam ◽  
High Energy ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Group V ◽  
X Ray ◽  
Molecular Beam Epitaxial ◽  
Wide Range ◽  
Molecular Beam Epitaxial Growth ◽  
Secondary Ion

ABSTRACTWe have investigated the molecular beam epitaxial growth of homoepitaxial InAs and GaSb and InAs/GaSb heterostructures on both the (111)A and (111)B orientations. Our studies have found that high quality GaSb epilayers can be grown on both the (111)A and (111l)B orientations over a wide range of growth temperatures and flux ratios. Reflection high energy electron diffr-action phase diagrams for GaSb [111[ are presented. InAs/GaSb heterostructures, simultaneously grown on (11l)A and (111)B orientations, have been investigated by secondary ion mass spectroscopy depth profiles and double crystal x-ray diffraction. Unintentional incorporation of the ‘second’ group-V element is found to be approximately three times greater in the (111)A orientation than in the (111)B for both species.

Index of Refraction Anisotropy in InGaAs/InP Heterostructures Measured by Ellipsometry

1989 ◽  
Vol 160 ◽  
Author(s):  
Brian R. Bennett ◽  
Jesús A. Del Alamo
Keyword(s):  
Optical Properties ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Index Of Refraction ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Asymmetric Pattern ◽  
Optical Effects

AbstractWe applied ellipsometry to characterize layers of InxGa1-xAs grown by molecular beam epitaxy on (001) InP. Samples with mismatched layers exhibit significant anisotropy in the index of refraction. We explain these observations by the presence of misfit dislocations which form in an asymmetric pattern. This results in asymmetric strain and, via piezo-optical effects, an anisotropy in the optical properties. This effect makes ellipsometry a more sensitive technique than double-crystal x-ray diffraction for detecting misfit dislocations in these heterostructures.

Tem Study of Temperature Influence on The Crystalline Quality of InGaAs/Si Epilayers

1992 ◽  
Vol 263 ◽  
Author(s):  
A. Vila ◽  
A. Cornet ◽  
J.R. Morante ◽  
D.I. Westwood
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Temperature Influence ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

ABSTRACTA Transmission Electron Microscopy (TEM) study of In0.53Ga0.47As Molecular Beam Epitaxy films grown at different temperatures onto misoriented Si (100) substrates is presented. The evolution of the density of the different kind of defects is discussed as a function of the growth temperature in the range between 200 and 500° C. The results are compared with the characterization techniques of Double Crystal X-Ray Diffraction and Hall effect.

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