X-ray topography and EBIC studies of misfit dislocations in strained layer structures

1987 ◽  
Vol 102 ◽  
Author(s):  
N. Hamaguchi ◽  
T. P. Humphreys ◽  
C. A. Parker ◽  
S. M. Bedair ◽  
B-L. Jiang ◽  
...  
Keyword(s):  
Critical Thickness ◽  
Misfit Dislocations ◽  
X Ray ◽  
Strained Layer ◽  
Layer Structures ◽  
Lattice Matched

ABSTRACTX-ray topography(XRT) and EBIC have been used to study the generation of misfit dislocations in strained layer structures. Two structures studied were GaAs1−yPy(y=0.15) film and SLS consisting of InxGa1−xAs(x=0.08) and GaAs1−y Py(y=0.16) layers. XRT and EBIC techniques gave consistent results for the behavior of dislocations. The value of the critical thickness for generation of misfit dislocations in the former was found to be few times larger than that in the latter. EBIC image showed that a SLS lattice matched to the substrate is effective in reducing defects originating from the substrate.

Mbe Growth of Strained-Layer InSb/InAlSb Structures

1990 ◽  
Vol 198 ◽  
Author(s):  
C.R. Whitehouse ◽  
C.F. Mcconville ◽  
G.M. Williams ◽  
A.G. Cullis ◽  
S.J. Barnett ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Critical Thickness ◽  
Multiple Quantum ◽  
Material System ◽  
X Ray Diffraction ◽  
Mbe Growth ◽  
X Ray ◽  
Strained Layer ◽  
Transmission Electron ◽  
Layer Structures

ABSTRACTThe MBE growth and related materials characterisation of InSb/InAlSb strained-layer structures is described. Band-gap considerations and critical thickness calculations are presented and indicate that this material system should offer considerable device potential. Detailed structural studies, performed using both transmission electron microscopy and X-ray diffraction, confirm the growth of high quality multiple quantum-wells, and 2K photoluminescence has shown corresponding energy upshifted transitions.

Misfit dislocations between boron-doped homoepitaxial films and diamond substrates studied by X-ray diffraction topography

2018 ◽  
Vol 51 (6) ◽  
pp. 1684-1690 ◽  
Author(s):  
Marina González-Mañas ◽  
Beatriz Vallejo
Keyword(s):  
Critical Thickness ◽  
Lattice Mismatch ◽  
Lattice Parameter ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Boron Doped Diamond ◽  
X Ray ◽  
Boron Doped ◽  
Slip Planes ◽  
Half Loop

Boron-doped diamond epilayers grown over diamond substrates have a different lattice parameter from the undoped diamond substrate, which introduces a lattice mismatch between substrates and epilayers. This can generate misfit dislocations at the interface when the epilayer reaches a certain critical thickness. For a boron concentration of about 1 × 1020 atoms cm−3, the calculated lattice mismatch is about 1.3 × 10−4 and the critical thickness is of the order of 0.2 µm. In the epilayers studied, grown over high-pressure high-temperature 1b (001) substrates, the lattice mismatch and the epilayer thickness are 1.3 × 10−4, 30 µm and 6.5 × 10−4, 4 µm. The epitaxial strain has been relaxed by the generation of two orthogonal misfit dislocation systems. These are edge dislocations parallel to the [100] and [010] directions with a Burgers vector making an angle of 45° with the (001) interface. Their lengths are 40–60 µm and their lineal densities 200–240 cm−1. They are heterogeneously nucleated, propagated in the form of half-loops along the slip planes (011) and (101), respectively, and related mainly to 〈111〉 threading dislocations emerging from octahedral growth sectors. Another kind of half-loop originates from the substrate growth sector boundaries. Limited X-ray topography has been demonstrated to be a very useful tool to discriminate between substrate and epilayer defects when their lattice mismatch is not sufficient to separate such defects in conventional Lang topography. X-ray section topography has confirmed the presence of [001] dislocations in the epilayers and the misfit half-loops related to threading dislocations propagating from the interface.

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.

Thickness Dependences of the Thermoelectric Properties in (001)KCl/PbTe/SnTe/PbTe Heterostructures

2003 ◽  
Vol 793 ◽  
Author(s):  
Elena I. Rogacheva ◽  
Olga N. Nashchekina ◽  
Svetlana G. Lyubchenko ◽  
Yegor O. Vekhov ◽  
Mildred S. Dresselhaus ◽  
...  
Keyword(s):  
Thermoelectric Properties ◽  
Carrier Mobility ◽  
Critical Thickness ◽  
Charge Carrier Mobility ◽  
General Character ◽  
Misfit Dislocations ◽  
Size Quantization ◽  
Thermoelectric Power Factor ◽  
Layer Structures ◽  
Pseudomorphic Growth

ABSTRACTThe dependences of the thermoelectric properties of (001)KCl/PbTe/SnTe/PbTe three-layer structures on the SnTe layer thickness (dSnTe = 0.5–6.0 nm) at a fixed thickness of PbTe layers were studied. It was established that the thickness dependences of the Seebeck coefficient, the Hall coefficient, electrical conductivity, charge carrier mobility, and the thermoelectric power factor are distinctly non-monotonic. Two possible reasons for this non-monotonic behavior of the thickness dependences of the thermoelectric properties are considered: the size quantization of the energy spectrum in a SnTe quantum well and / or the formation of edge misfit dislocations at the interfaces after reaching the critical thickness, which corresponds to the transition from a pseudomorphic growth to the introduction of misfit dislocations at the interfaces. It is suggested that the observed effect has a general character and should be taken into account when optimizing thermoelectric properties of superlattices.

Asymmetric Mosaic Spread During Relaxation in SiGe/ Si Strained Layer Superlattices Grown on Miscut Substrates

1995 ◽  
Vol 379 ◽  
Author(s):  
S. Nam ◽  
M. S. Goorsky
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Critical Thickness ◽  
Chemical Vapor ◽  
Misfit Dislocations ◽  
Satellite Peak ◽  
Strained Layer ◽  
Mosaic Spread ◽  
Peak Intensity ◽  
Strained Layer Superlattices

ABSTRACTThe evolution of defects in SiGe/Si strained layer superlattices (SLS)-with thickness and composition near the critical thickness -was investigated. The structures were grown on 2° miscut (001) substrates by ultrahigh vacuum chemical vapor deposition. The samples were then annealed between 700 °C and 900 °C. After annealing, the satellite peak intensity from double axis diffraction decreased and triple axis diffraction showed that this decreased intensity was due to increased mosaic structure. Interestingly, for some of the annealed samples, the (004) reciprocal space maps showed an asymmetric mosaic spread, indicating a preferential tilt. This result stems from a preferential propagation of certain types of misfit dislocations due to the substrate miscut.

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.

Strain Relaxation Via Interface Nucleation of Misfit Dislocations in Intermixing Layers

1992 ◽  
Vol 263 ◽  
Author(s):  
Hyo-Hoon Park ◽  
Jung Kee Lee ◽  
El-Hang Lee ◽  
Jeong Yong Lee ◽  
Soon-Ku Hong
Keyword(s):  
Electron Microscopy ◽  
Homogeneous Nucleation ◽  
Critical Thickness ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
Semiconductor Heterostructures ◽  
Misfit Dislocations ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Lattice Matched

ABSTRACTThe strain relaxation mechanism via the homogeneous nucleation of misfit dislocations from interface during interdiffusion in lattice-matched semiconductor heterostructures has been investigated. Transmission electron microscopy studies in intermixed GaInAsP/InP heterostructures revealed that the critical interdiffusion depth for the nucleation of 90° 1/6<112> partial dislocations from a tensile interface is much shallower than that of 60° 1/2<110> perfect dislocations from a compressive interface. A critical thickness model for the interface nucleation of these dislocations is developed as a modification of the classical surface nucleation'model.

Mechanics of Elastic Dislocations in Strained Layer Structures

1988 ◽  
Vol 130 ◽  
Author(s):  
L. B. Freund ◽  
A. Bower ◽  
J. C. Ramirez
Keyword(s):  
Critical Thickness ◽  
Strain Relaxation ◽  
Continuum Theory ◽  
Growth Surface ◽  
Threading Dislocation ◽  
Strained Layer ◽  
Periodic Arrays ◽  
Layer Structures ◽  
Surface Irregularities ◽  
Generalized Driving Force

AbstractApplication of the elastic continuum theory of dislocations to modeling of phenomena associated with elastic strain relaxation in strained layer epitaxial heterostructures is discussed. The concept of critical thickness for onset of strain relaxation in a strained epitaxial layer is first reviewed, and some extensions to periodic arrays of dislocations and to multiple layers are described. Then, two issues are addressed that arise when the assumptions underlying the critical thickness concept are not met. One issue concerns the nucleation of dislocations at the growth surface of an epitaxial film, particularly the influence of surface irregularities on the activation energy for surface nucleation. A second issue concerns the kinetics of glide of a threading dislocation as it lays down an interface misfit dislocation when the layer thickness exceeds the critical thickness. A generalized driving force for the glide process is defined, and a relationship between this force and the glide speed is proposed.

Relaxation of Metastable Semiconductor Strained-Layer Structures by Plastic Flow

1987 ◽  
Vol 103 ◽  
Author(s):  
Brian W. Dodson ◽  
Jeffrey Y. Tsao
Keyword(s):  
Plastic Flow ◽  
Continuum Model ◽  
Critical Thickness ◽  
Misfit Strain ◽  
Relaxation Behavior ◽  
Strained Layer ◽  
Metastable Structures ◽  
Layer Structures ◽  
Bulk Diamond ◽  
Excess Stress

ABSTRACTThe relaxation of misfit strain in metastable structures by plastic flow is described using a continuum model based on Haasen's picture of plastic flow in bulk diamond-phase semiconductors and the concept of excess stress. This model provides a unified explanation of the equilibrium critical thickness, the relaxation behavior of metastable strained-layer structures, and the “metastable” critical thicknesses reported in many semiconductor strained-layer geometries.

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