Confinement of Threading Dislocations in Simox with a GeSi Strained Layer

1990 ◽  
Vol 198 ◽  
Author(s):  
F. Namavar ◽  
E. Cortesi ◽  
D.L. Perry ◽  
E.A. Johnson ◽  
N.M. Kalkhoran ◽  
...  
Keyword(s):  
Alloy Layer ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Epitaxial Silicon ◽  
Strained Layers ◽  
Strained Layer ◽  
Si Substrates ◽  
Plane View ◽  
Gesi Layer

ABSTRACTWe have investigated improving the crystalline quality of epitaxial silicon grown on SIMOX by confining threading dislocations in the original Si top layer using a GeSi strained layer. Epitaxial Si/GeSi/Si structures were grown by CVD on SIMOX and Si substrates with a GeSi alloy layer about 1000 − 1500 angstroms thick with Ge concentrations of about 0−20%. A Ge concentration in the alloy layer of about 5.5% or higher appears to be necessary in order to bend any of the threading dislocations from the original SIMOX top layer. For a higher Ge concentration of about 16%, most of the threading dislocations appear to be bent and confined by the GeSi layer. In addition, the GeSi strained layers grown by CVD (at about 1000°C) appear to be high quality and no misfit dislocations were observed in the regions studied by XTEM and plane view TEM.

OPTICAL IMAGING OF DISLOCATIONS IN STRAINED—LAYER SUPERLATTICES AND LATTICE—MISMATCHED EPILAYERS

1985 ◽  
Vol 56 ◽  
Author(s):  
P. L. GOURLEY ◽  
R. M. BIEFELD ◽  
L. R. DAWSON
Keyword(s):  
Optical Imaging ◽  
Critical Thickness ◽  
Optical Quality ◽  
Thin Layers ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Semiconductor Alloys ◽  
Strained Layer ◽  
Strained Layer Superlattices

AbstractWe have developed a convenient photoluminescence microimaging technique to probe misfit dislocations in epitaxially grown semiconductor alloys and multilayers. Using this technique, we have examined the microscopic optical quality of thick (~ 1 μm ) III-V semiconductor epitaxial layers, mismatched to their substrates. The layers includeseveral kinds of [100] strained-layer superlattices (GaP/GaAsxP1-x on GaP and GaAs/GaAs. P on GaAs grown by MOCVD, and GaAs/In Ga1-x As on GaAs grown by MBE) and associated alloys. For each type of superlalti e, we have studied a large number of samples corresponding to different compositions and layer thicknesses. The results show that misfit dislocations can be completely eliminated in the uppermost layers of the strained-layer superlattices if these structures have thin layers, less than the critical thickness for elastic accommodation, and sufficient numbers of interfaces to block threading dislocations.

Defect Reduction in GaAs Epilayers on Si Substrates Using Strained Layer Superlattices

1987 ◽  
Vol 91 ◽  
Author(s):  
N. El-Masry ◽  
N. Hamaguchi ◽  
J.C.L. Tarn ◽  
N. Karam ◽  
T.P. Humphreys ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Defect Reduction ◽  
Strained Layer ◽  
Si Substrates ◽  
Density Of Dislocations ◽  
Strained Layer Superlattice ◽  
Strained Layer Superlattices

ABSTRACTInxGa11-xAs-GaAsl-yPy strained layer superlattice buffer layers have been used to reduce threading dislocations in GaAs grown on Si substrates. However, for an initially high density of dislocations, the strained layer superlattice is not an effective filtering system. Consequently, the emergence of dislocations from the SLS propagate upwards into the GaAs epilayer. However, by employing thermal annealing or rapid thermal annealing, the number of dislocation impinging on the SLS can be significantly reduced. Indeed, this treatment greatly enhances the efficiency and usefulness of the SLS in reducing the number of threading dislocations.

Short-period (Si14 / Si0.75 Ge0.25)20 Superlattices for the Growth of High-quality Si0.75 Ge0.25

2003 ◽  
Vol 765 ◽  
Author(s):  
M.M. Rahman ◽  
T. Tambo ◽  
C. Tatsuyama
Keyword(s):  
Low Temperature ◽  
Alloy Layer ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
Strained Layers ◽  
Temperature Growth ◽  
Low Temperature Growth ◽  
Defect Sites ◽  
Short Period ◽  
Different Temperatures

AbstractIn the present experiment, we have grown 2500-Å thick Si0.75Ge0.25 alloy layers on Si(001) substrate by MBE process using a short-period (Si14/Si0.75Ge0.25)20 superlattice (SL) as buffer layers. In the SL layers, first a layer of 14 monolayers (MLs) of Si (thickness about 20Å) then a thin layer of Si0.75Ge0.25 (thickness 5-6Å) were grown. This Si/(Si0.75Ge0.25) bilayers were repeated for 20 times. The buffer layers were grown at different temperatures from 300-400°C and the alloy layers were then grown at 500°C on the buffer layers. The alloy layer showed low residual strain (about -0.16%) and smooth surface (rms roughness ~15Å) with 300°C grown SL buffer. Low temperature growth of Si in SL layer introduces point defects and low temperature growth of Si1-xGex in SL layer reduces the Ge segregation length, which leads to strained SL layer formation. Strained layers are capable to make barrier for the propagation of threading dislocations and point defect sites can trap the dislocations.

Stress Relaxation in Uniquely Oriented SiGe/Si Epitaxial Layers

1999 ◽  
Vol 594 ◽  
Author(s):  
M. E. Ware ◽  
R. J. Nemanich
Keyword(s):  
Stress Relaxation ◽  
Surface Morphology ◽  
Strain Relaxation ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Deposited Films

AbstractThis study explores stress relaxation of epitaxial SiGe layers grown on Si substrates with unique orientations. The crystallographic orientations of the Si substrates used were off-axis from the (001) plane towards the (111) plane by angles, θ = 0, 10, and 22 degrees. We have grown 100nm thick Si(1−x) Ge(x) epitaxial layers with x=0.3 on the Si substrates to examine the relaxation process. The as-deposited films are metastable to the formation of strain relaxing misfit dislocations, and thermal annealing is used to obtain highly relaxed films for comparison. Raman spectroscopy has been used to measure the strain relaxation, and atomic force microscopy has been used to explore the development of surface morphology. The Raman scattering indicated that the strain in the as-deposited films is dependent on the substrate orientation with strained layers grown on Si with 0 and 22 degree orientations while highly relaxed films were grown on the 10 degree substrate. The surface morphology also differed for the substrate orientations. The 10 degree surface is relatively smooth with hut shaped structures oriented at predicted angles relative to the step edges.

Observation of GaAs/Si Epitaxial Interfaces by Atomic Resolution Electron Microscopy

1986 ◽  
Vol 67 ◽  
Author(s):  
N. Otsuka ◽  
C. Choi ◽  
Y. Nakamura ◽  
S. Nagakura ◽  
R. Fischer ◽  
...  
Keyword(s):  
Substrate Surface ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Gaas Films ◽  
Substrate Surfaces

ABSTRACTRecent studies have shown that high quality GaAs films can be grown by MBE on Si substrates whose surfaces are slightly tilted from the (100) plane. In order to investigate the effect of the tilting of substrate surfaces on the formation of threading dislocations, the GaAs/Si epitaxial interfaces have been observed with a 1 MB ultra-high vacuum, high voltage electron microscope. Two types of misfit dislocations, one with Burgers vectors parallel to the interface and the other with Burgers vectors inclined from the interface, were found in these epitaxial interfaces. The observation of crosssectional samples perpendicular to each other has shown that the tilting of the substrate surface directly influences the generation of these two types of misfit dislocations. The mechanism of the reduction of threading dislocations by the tilting of the substrate surface is discussed based on these observations.

scholarly journals The Structure of GaAs/Si(211) Heteroepitaxial Layers

1987 ◽  
Vol 91 ◽  
Author(s):  
Zuzanna Liliental-Weber ◽  
E.R. Weber ◽  
J. Washburn ◽  
T.Y. Liu ◽  
H. Kroemer
Keyword(s):  
Buffer Layer ◽  
Surface Preparation ◽  
Gaas Layer ◽  
Misfit Dislocations ◽  
Strained Layer ◽  
Si Substrates ◽  
Density Of Dislocations ◽  
Gaas Buffer Layer ◽  
Graded Layers ◽  
Strained Layer Superlattices

ABSTRACTGallium arsenide films grown on (211)Si by molecular-beam epitaxy have been investigated using transmission electron microscopy. The main defects observed in the alloy were of misfit dislocations, stacking faults, and microtwin lamellas. Silicon surface preparation was found to play an important role on the density of defects formed at the Si/GaAs interface.Two different types of strained-layer superlattices, InGaAs/InGaP and InGaAs/GaAs, were applied either directly to the Si substrate, to a graded layer (GaP-InGaP), or to a GaAs buffer layer to stop the defect propagation into the GaAs films. Applying InGaAs/GaAs instead of InGaAs/InGaP was found to be more effective in blocking defect propagation. In all cases of strained-layer superlattices investigated, dislocation propagation was stopped primarily at the top interface between the superlattice package and GaAs. Graded layers and unstrained AlGaAs/GaAs superlattices did not significantly block dislocations propagating from the interface with Si. Growing of a 50 nm GaAs buffer layer at 505°C followed by 10 strained-layer superlattices of InGaAs/GaAs (5 nm each) resulted in the lowest dislocation density in the GaAs layer (∼;5×l07/cm2) among the structures investigated. This value is comparable to the recently reported density of dislocations in the GaAs layers grown on (100)Si substrates [8]. Applying three sets of the same strained layersdecreased the density of dislocations an additional ∼2/3 times.

High Quality GaAs on Si and its Application to a Solar Cell

1988 ◽  
Vol 144 ◽  
Author(s):  
Yoshiro Ohmachi ◽  
Yoshiaki Kadota ◽  
Yoshio Watanabe ◽  
Hiroshi Okamoto
Keyword(s):  
Solar Cell ◽  
Critical Thickness ◽  
High Quality ◽  
Strained Layer ◽  
Cyclic Annealing ◽  
Si Substrates ◽  
Gaas On Si ◽  
Strained Layer Superlattice ◽  
Buffer Structure

ABSTRACTEpitaxial growth using thermal annealing and a strained layer superlattice is studied to obtain high-quality GaAs device layers on Si substrates. Crystalline quality of GaAs-on-Si is found to improve with thermal cyclic annealing at temperatures higher than the growth temperature and cooling down to 300°C. It is also found that the optimum InGaAs/GaAs strained layer superlattice buffer structure is one whose total thickness is several times the calculated critical thickness for the average In-mole fraction of the SLS buffer. Configurations and structures of dislocation reductions are ex-amined by TEM observations. A GaAs solar cell is successfully constructed and is found to show total area efficiencies of 18.3% under AM 0 and 20.0% under AM 1.5 conditions.

MoirÉ Pattern Studies of Thin Layers Deposited on (001)Si Substrates: Cases of Tisi2 and GaAs.

1989 ◽  
Vol 148 ◽  
Author(s):  
A. Rocher ◽  
X. Wallart ◽  
M.N. Charasse
Keyword(s):  
Three Dimensional ◽  
Thin Layers ◽  
Dislocation Network ◽  
Threading Dislocations ◽  
Si Substrates ◽  
Moire Pattern ◽  
Moiré Pattern ◽  
Dimensional Growth ◽  
Residual Strains

ABSTRACTMoiré pattern images have been used to investigate the crystalline quality of thin films deposited on (100)Si substrates. Observations performed on TiSi2 show a three-dimensional growth process and two different epitaxial modes. In the case of GaAs epilayers, it is shown that the residual strains are not uniformly distributed in the layer. Residual strain and threading dislocations are related to imperfections of the misfit dislocation network.

Propagation of Dislocations Through GeSi/Si Strained Layers and Superlattices

1988 ◽  
Vol 116 ◽  
Author(s):  
R. Hull ◽  
J.C. Bean ◽  
R.E. Leibenguth
Keyword(s):  
Single Layer ◽  
Dislocation Nucleation ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Activation Barriers ◽  
Strained Layer ◽  
Growth Activation ◽  
Si Epitaxy ◽  
Strained Layer Superlattices

AbstractWe describe in-situ transmission electron microscope observations of the relaxation of strained layer GeSi/Si epitaxy. Dynamic observations of misfit dislocations in these structures reveal that dislocation nucleation and growth activation barriers, as well as interactions, limit the rate at which strain is relieved. The equivalence of threading and misfit dislocations in this system is demonstrated. Extension of the principles learnt from these single layer experiments to threading dislocation propagation through multilayer structures, enables us to understand the relative inefficiency of GeSi/Si strained layer superlattices in blocking threading dislocations.

Observation of GaAs/Si Interface by Tem: Effect of Annealing on the Structure

1987 ◽  
Vol 102 ◽  
Author(s):  
H. Heral ◽  
A. Rocher ◽  
M. N. Charasse ◽  
A. Georgakilas ◽  
J. Chazelas ◽  
...  
Keyword(s):  
Cross Section ◽  
Gaas Layer ◽  
Heat Treatments ◽  
Interface Roughness ◽  
Crystalline Quality ◽  
Threading Dislocations ◽  
Section Technique ◽  
Before And After ◽  
Plane View

ABSTRACTWe present in this paper the effect of heat treatments applied to a 400 nm GaAs layer grown by MBE on a (001) Silicon substrate. These heat treatments have been applied during or after the growth of the GaAs, in order to improve the crystalline quality of the layer. RBS and TEM observations have been performed to study the improvement of the crystalline quality of the GaAs layer. Specimens, prepared by cross-section technique along both (110) and (170) planes and plane view, have been studied by TEM. Observations of cross-section by HREM show an interface roughness of about 1.5 nm before and after heat treatments. A roughness, observed also by RHEED, appears in the first stage of growth. Although the density of threading dislocations decreases after heat treatments.

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