Recent Advances in the Modeling of Strain Relaxation and Dislocation Dynamics in InGaAs/GaAs (001) Heterostructures

2020 ◽  
Vol 29 (01n04) ◽  
pp. 2040005
Author(s):  
J. E. Ayers ◽  
Tedi Kujofsa ◽  
Johanna Raphael ◽  
Md Tanvirul Islam
Keyword(s):  
Strain Relaxation ◽  
Practical Interest ◽  
Dislocation Dynamics ◽  
Material System ◽  
Multilayered Structures ◽  
Physical Description ◽  
Dislocation Interactions ◽  
Graded Layers ◽  
Strained Layer Superlattices ◽  
Compositional Grading

In this paper we describe state-of-the-art approaches to the modeling of strain relaxation and dislocation dynamics in InGaAs/GaAs (001) heterostructures. Current approaches are all based on the extension of the original Dodson and Tsao plastic flow model to include compositional grading and multilayers, dislocation interactions, and differential thermal expansion. Important recent break-throughs have greatly enhanced the utility of these modeling approaches in four respects: i) pinning interactions are included in graded and multilayered structures, providing a better description of the limiting strain relaxation as well as the dislocation sidewall gettering; ii) a refined model for dislocation-dislocation interactions including zagging enables a more accurate physical description of compositionally-graded layers and step-graded layers; iii) inclusion of back-and-forth weaving of dislocations provides a better description of dislocation dynamics in structures containing strain reversals, such as strained-layer superlattices or overshoot graded layers; and iv) the compositional dependence of the model kinetic parameters has been elucidated for the InGaAs material system, allowing more accurate modeling of heterostructures with wide variations in composition. We will describe these four key advances and illustrate their applications to heterostructures of practical interest.

A Zagging and Weaving Model for Dislocation Interactions in Heterostructures Containing Strain Reversals

2020 ◽  
Vol 29 (01n04) ◽  
pp. 2040003
Author(s):  
Tedi Kujofsa ◽  
J. E. Ayers
Keyword(s):  
Semiconductor Device ◽  
Dislocation Dynamics ◽  
Physical Models ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Strained Layer ◽  
Device Structures ◽  
Dislocation Interactions ◽  
Dislocation Behavior ◽  
Strained Layer Superlattices

Strained-layer superlattices (SLSs) have been used to modify the threading dislocation behavior in metamorphic semiconductor device structures; in some cases they have even been used to block the propagation of threading dislocations and are referred to in these applications as “dislocation filters.” However, such applications of SLSs have been impeded by the lack of detailed physical models. Here we present a “zagging and weaving” model for dislocation interactions in multilayers and strained-layer superlattices, and we demonstrate the use of this model to the threading dislocation dynamics in InGaAs/GaAs (001) structures containing SLSs.

Atomistic and Continuum Studies of Diffusional Creep and Associated Dislocation Mechanisms in thin Films on Substrates

2003 ◽  
Vol 779 ◽  
Author(s):  
Markus J. Buehler ◽  
Alexander Hartmaier ◽  
Huajian Gao
Keyword(s):  
Thin Films ◽  
Stress Field ◽  
Grain Boundary ◽  
Large Scale ◽  
Strain Relaxation ◽  
Dislocation Dynamics ◽  
Biaxial Stress ◽  
Diffusional Creep ◽  
Material Transport ◽  
Dynamics Simulations

AbstractMotivated by recent theoretical and experimental progress, large-scale atomistic simulations are performed to study plastic deformation in sub-micron thin films. The studies reveal that stresses are relaxed by material transport from the surface into the grain boundary. This leads to the formation of a novel defect identified as diffusion wedge. Eventually, a crack-like stress field develops because the tractions along the grain boundary relax, but the adhesion of the film to the substrate prohibits strain relaxation close to the interface. This causes nucleation of unexpected parallel glide dislocations at the grain boundary-substrate interface, for which no driving force exists in the overall biaxial stress field. The observation of parallel glide dislocations in molecular dynamics studies closes the theory-experiment-simulation linkage. In this study, we also compare the nucleation of dislocations from a diffusion wedge with nucleation from a crack. Further, we present preliminary results of modeling constrained diffusional creep using discrete dislocation dynamics simulations.

X-Ray Investigation of Strain Relaxation in Short-Period SimGen Superlattices using Reciprocal Space Mapping

1993 ◽  
Vol 298 ◽  
Author(s):  
P. Hamberger ◽  
E. Koppensteiner ◽  
G. Bauer ◽  
H. Kibbel ◽  
H. Presting ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Reciprocal Lattice ◽  
Reciprocal Space ◽  
Lattice Points ◽  
Reciprocal Space Mapping ◽  
Double Crystal ◽  
X Ray ◽  
Short Period ◽  
Integrated Intensity ◽  
Strained Layer Superlattices

AbstractThe optoelectronic properties of SimGen strained layer superlattices (SLS's) depend strongly on the structural perfection. We used double crystal and triple axis x-ray diffractometry to characterize the structural properties of short period Si9Ge6 SLS's grown on about lμm thick step-graded SiGe alloy buffers. As grown SLS's and samples annealed subsequently at 550°C, 650°C and 780°C for 60 mmn were investigated. Precise strain data were extracted from two-dimensional reciprocal space maps around (004) and (224) reciprocal lattice points. These data were used as refined input parameters for the dynamical simulation of the integrated intensity along the qll[004] direction. Annealing causes interdiffusion as indicated by the decreasing superlattice (SL)-satellite peak intensities and by the change of the Si/Ge thickness ratio. However, the full width at half maximum of the SL satellite peaks does not change significantly with annealing up to 650°C. The in-plane SL lattice constant in both samples is increased only slighty by annealing (< 9×10−3 Å). Consequently the interface intermixing due to interdiffusion is the main cause for the shift of the luminescence energy to higher values in these annealed samples.

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.

Plastic Deformation of Textured Zircaloy 2

2011 ◽  
Vol 702-703 ◽  
pp. 838-841
Author(s):  
Santosh Kumar Sahoo ◽  
V. D. Hiwarkar ◽  
Prita Pant ◽  
Indradev Samajdar ◽  
Karri V. Mani Krishna ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Room Temperature ◽  
Deformation Behaviour ◽  
Dislocation Dynamics ◽  
Dynamics Simulation ◽  
Distinct Class ◽  
Dislocation Interactions ◽  
Temperature Deformations ◽  
Grain Misorientation

The present study deals with deformation behaviour of textured Zircaloy 2 with two dominant orientations: basal and non-basal. During initial stages (20%), two distinct class of grains were observed – non-deforming/non-fragmenting grains and deforming/fragmenting grains. The so-called non- deforming/non-fragmenting grains remain equiaxed even after 50% of deformation. They also have insignificant in-grain misorientation developments and have more residual stresses. Dislocation dynamics simulation showed that the dislocation interactions/mobility is insignificant in basal orientations at room temperature deformations.

scholarly journals Dislocation dynamics of strain relaxation in epitaxial layers

2001 ◽  
Vol 89 (11) ◽  
pp. 6069-6072 ◽  
Author(s):  
T. C. Wang ◽  
Y. W. Zhang ◽  
S. J. Chua
Keyword(s):  
Strain Relaxation ◽  
Dislocation Dynamics ◽  
Epitaxial Layers

Strain Relief in InxGa1−xAs/GaAs Multiple Layer Systems

1992 ◽  
Vol 263 ◽  
Author(s):  
V. Krishnamoorthy ◽  
Y.W. Lin ◽  
R.M. Park
Keyword(s):  
Substrate Material ◽  
Threading Dislocation ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Strain Relief ◽  
Multilayer Systems ◽  
Critical Composition ◽  
Multiple Layer ◽  
Graded Layers ◽  
Strained Layer Superlattices

ABSTRACTIn a recent paper[l] we presented the notion of a “critical composition” of InxGa1−xAs (x=0.18) which when exceeded results in threading dislocation evolution in InxGa1−xAs (x ≥ 0.18) material grown on GaAs. For InxGa1−xAs compositions below x=0.18, threading dislocation evolution occurs in the GaAs substrate material but not in the InxGa1−xAs epitaxial layer material, this phenomenon being attributed to a yield strength mismatch in favor of InxGa1−xAs at the epilayer growth temperature.In this paper we describe recent results concerning an extension of this work to the study of strain relief in multiple layer systems. It was found that large x (x-0.5) InxGa1−xAs/GaAs layers can be grown having extremely low dislocation densities (<104/cm2 ) by step increasing the InxGa1−xAs composition at a series of InxGa1−xAs/InyGa1-yAs heterointerfaces such that a “critical composition difference” is not exceeded at each heterointerface. High resolution x-ray diffraction analysis was used to determine the extent of relaxation in each layer of these multilayer systems. As evidenced by cross-sectional TEM analysis, dislocations propagate only in the underlying material at each heterointerface for suitably selected compositional differences which results in the top InxGa1−xAs layer in such multiple layer schemes having a low dislocation density. It is to be noted that conventional methods for blocking dislocations such as strained layer superlattices and compositionally graded layers were not employed in our multilayer systems.

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