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.

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.

MBE Growth of Low Dislocation and High Mobility GaAs-on-Si

1986 ◽  
Vol 67 ◽  
Author(s):  
Jhang Woo Lee
Keyword(s):  
Layer Structure ◽  
High Mobility ◽  
Gaas Layer ◽  
Buffer Layers ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Molecular Beam Epitaxial ◽  
Transmission Electron ◽  
Low Dislocation Density ◽  
Molecular Beam Epitaxial Growth

ABSTRACTData is presented on the optimization of several molecular beam epitaxial growth processes to provide low dislocation density and high mobility GaAs single crystals on (100) Si wafers. The substrate tilt angle, the growth temperature, and the first buffer layer structure, were investigated Tor this purpose. Using Hall measurements the GaAs layers grown on 2 or 3-degree tilt (100) Si showed consistently high mobilities which are equivalent to the homoepitaxial GaAs mobility. Transmission electron microscopy (TEM) revealed that on tilted (100) Si substrates most of the misfit dislocations were confined within the first 50 Å GaAs layer by forming a type of edge dislocation at the Si surface step edges. Also low temperature grown buffer layers always gave better morphologies and lower etch pit densities while keeping the high mobilities on overgrown GaAs layers.

Growth and Characterizations of Gaas on Inp with Different Buffer Structures by Molecular Beam Epitaxy

1989 ◽  
Vol 148 ◽  
Author(s):  
Xiaoming Liu ◽  
Henry P. Lee ◽  
Shyh Wang ◽  
Thomas George ◽  
Eicke R. Weber ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Gaas Layer ◽  
Optical Quality ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Layer Structures ◽  
Gaas Films ◽  
Initial Deposition ◽  
Strained Layer Superlattices

ABSTRACTWe report the growth and characterizations of 31μm thick GaAs films grown on (100) InP substrates by MBE employing different buffer layer structures during the initial deposition. The buffer layer structures under study are: 1) GaAs layer grown at low temperature; 2) GaAs layer grown at low temperature plus two sets of In0.08Ga0.92As/GaAs strained layer superlattices (SLS) and 3) a transitional compositionally graded InxGal-xAs layer between the InP substrate and the GaAs film. After the buffer layer deposition, the growth was continued by conventionalMBE to a total thickness of 3μm for all samples. From the 77K photoluminescence (PL) measurement, it was found that the sample with SLS layers has the highest PL intensity and the narrowest PL linewidth. Cross-sectional transmission electron microscopy (TEM) studies showed that the SLS is effective in reducing the propagation of threading dislocations and explains the observed superior optical quality from the PL measurement.

The Creation of Misfit Dislocations; A Study of InGaAs Alloys on GaAs Substrates

1990 ◽  
Vol 202 ◽  
Author(s):  
Peter J Goodhew ◽  
Philip Kightley
Keyword(s):  
Measurement Error ◽  
Buffer Layer ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Strained Layer ◽  
Gaas Substrates ◽  
Angle Point ◽  
Point Of Intersection ◽  
Edge Dislocations ◽  
Line Direction

ABSTRACTGrowth onto vicinal substrates causes 60° misfit dislocations to adopt line directions away from <110> in order for them to maintain their presence within the substrate to strained layer interface. Observations show that for the growth of an on-axis [001]wafer the dislocations have a line direction, within measurement error, exactly [110] or [-110] and two sets of orthogonal dislocations are generated. When grown onto a wafer that is cut off-axis toward [010] four sets of dislocations are generated. The two sets of dislocations in each direction converge to form low angle intersections from which edge dislocations are formed. These edge dislocations can become very long by the glide out of the interface plane of the component 60° dislocations. This ‘zipping-up’ to form the edge components only occurs in one direction from the low angle point of intersection and the edge segments are exclusively generated in the buffer layer. Their density and penetration are a function of thickness and composition of the mismatched epilayer. The mechanisms by which the dislocations adopt line directions away from <110> and why they zip-up from the intersection in only one direction are discussed.

Tem Assessment of Defects in (CdHg)Te Heterostructures

1990 ◽  
Vol 216 ◽  
Author(s):  
S.G. Lawson-Jack ◽  
I.P. Jones ◽  
D.J. Williams ◽  
M.G. Astles
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
High Density ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Burgers Vector ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Interfacial Plane

ABSTRACTTransmission electron microscopy has been used to assess the defect contents of the various layers and interfaces in (CdHg) Te heterostructures. Examination of cross sectional specimens of these materials suggests that the density of misfit dislocations at the interfaces is related to the layer thicknesses, and that the high density of dislocations which are generated at the GaAs/CdTe interface are effectively prevented from penetrating into the CdHgTe epilayer by a 3um thick buffer layer. The majority of the dislocations in the layers were found to have a Burgers vector b = a/2<110> and either lie approximately parallel or inclined at an angle of ∼ 60° to the interfacial plane.

X‐ray diffraction analysis of buffer layer effects on lattice distortions of strained layer superlattices

1987 ◽  
Vol 62 (3) ◽  
pp. 1124-1127 ◽  
Author(s):  
K. Kamigaki ◽  
H. Sakashita ◽  
H. Kato ◽  
M. Nakayama ◽  
N. Sano ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Buffer Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strained Layer ◽  
Lattice Distortions ◽  
Strained Layer Superlattices

A Tem Study of Defect Structure in GaAs Film on Si Substrate

1993 ◽  
Vol 325 ◽  
Author(s):  
Sahn Nahm ◽  
Hee-Tae Lee ◽  
Sang-Gi Kim ◽  
Kyoung-Ik Cho
Keyword(s):  
Buffer Layer ◽  
Defect Structure ◽  
Stacking Faults ◽  
Misfit Dislocations ◽  
Gaas Film ◽  
Si Substrate ◽  
Moiré Fringes ◽  
Gaas Films ◽  
Layer Stacking ◽  
Gaas Buffer Layer

AbstractFor the GaAs buffer layer deposited on Si substrate at 80°C and annealed at 300°C for 10 min, the size of most GaAs islands was observed as ∼ 10 nm but large islands (∼ 40 nm) were also seen. According to the calculation of spacing of moire fringes, large GaAs islands are considered to be rotated about 4 ° with respect to the Si substrate normal. However, for the main GaAs film overgrown on the GaAs buffer layer at 580 °C, moire fringes with the spacing of 5 nm (GaAs film without rotation) completely covered the surface of Si substrate. Misfit dislocations and stacking faults were already formed at the growth stage of buffer layer. Stacking faults and misfit dislocations consisting of Lomer and 60 ° dislocations were observed in GaAs films grown at 580 °C. However, after rapid thermal annealing at 900 °C for 10 sec, only Lomer dislocations with 1/2[110] and 1/2[-110] Burgers vectors were observed.

Growth of (GaAs)1−x (Si2)x Metastable Alloys using Migration-Enhanced Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
T. Sudersena Rao ◽  
Y. Horikoshi
Keyword(s):  
Buffer Layers ◽  
Double Crystal ◽  
Cross Sectional ◽  
Strained Layer ◽  
Si Substrates ◽  
Migration Enhanced Epitaxy ◽  
Strained Layer Superlattice ◽  
Metastable Alloys ◽  
Si Content ◽  
Strained Layer Superlattices

ABSTRACTEpitaxial (GaAs)1−x (Si2)x metastable alloys have been grown on GaAs (100) substrates using Migration-Enhanced Epitaxy in the composition range of 0<x<0.25. The lattice constant a0 of the alloys was found to decrease with increasing Si content from 0.56543nm at x=0 to 0.5601nm at x=0.25. Double-crystal x-ray diffraction rocking curve measurements and cross-sectional transmission electron microscopy studies made on a 10 period (GaAs)1−x(Si2)x/GaAs strained layer superlattice indicated sharp and abrupt interfaces. High crystalline quality GaAs has been grown on Si substrates using (GaAs)0.80(Si2)0.20/GaAs strained layer superlattices as buffer layers.

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.

Photoluminescence of InP/GaAs/Si Heterostructures

1988 ◽  
Vol 144 ◽  
Author(s):  
V.P. Mazzi ◽  
N.M. Haegel ◽  
S.M. Vernon ◽  
V.E. Haven
Keyword(s):  
Residual Stress ◽  
Thermal Expansion ◽  
Low Temperature ◽  
Band Gap ◽  
Buffer Layer ◽  
Thermal Expansion Mismatch ◽  
Si Substrates ◽  
Gaas Buffer Layer ◽  
Buffer Layer Thickness ◽  
Low Temperature Photoluminescence

ABSTRACTLow temperature photoluminescence results from MOCVD epitaxial InP grown on GaAs/Si substrates are presented as a function of thickness of the GaAs buffer layer. As a consequence of thermal expansion mismatch of the heterostructure, the InP layer contains residual stress which causes the band gap to shift and splits the valence band degeneracy of the mj = ± 3/2 and the mj = ± 1/2 bands. Both the shifting and splitting phenomena are clearly seen in tite PL results and are shown to depend on the GaAs buffer layer thickness.

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