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

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.

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.

Strain relaxation of AlxGa1−xN epitaxial layers on GaN and SiC substrates

1999 ◽  
Vol 286 (1-2) ◽  
pp. 284-288 ◽  
Author(s):  
J Domagala ◽  
M Leszczynski ◽  
P Prystawko ◽  
T Suski ◽  
R Langer ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Epitaxial Layers

Strain relaxation in AlN epitaxial layers grown on GaN single crystals

1999 ◽  
Vol 205 (1-2) ◽  
pp. 31-35 ◽  
Author(s):  
R Langer ◽  
A Barski ◽  
A Barbier ◽  
G Renaud ◽  
M Leszczynski ◽  
...  
Keyword(s):  
Single Crystals ◽  
Strain Relaxation ◽  
Epitaxial Layers

Dislocations and Internal Stresses in Thin Films: A Discrete-Continuum Simulation

1999 ◽  
Vol 578 ◽  
Author(s):  
C. Lemarchand ◽  
B. Devincre ◽  
L.P. Kubin ◽  
J.L. Chaboche
Keyword(s):  
Thin Films ◽  
Critical Stress ◽  
Image Force ◽  
Dislocation Dynamics ◽  
Internal Stresses ◽  
Epitaxial Layers ◽  
Free Standing ◽  
Misfit Stress ◽  
Substrate Interface ◽  
Film Substrate

The plasticity of thin films and layers is of considerable technological interest. For instance, the relaxation of internal stresses in semiconducting epitaxial layers has been the object of many studies [1, 2]. This relaxation is usually treated via the concept of critical thickness, the latter being defined as the maximum layer thickness below which dislocations cannot spontaneously move and relax the internal stresses. The various internal stresses present in epitaxial layers (e.g. the misfit and elastic incompatibility stresses at the film/substrate interface and the image force in a free-standing film) can be computed within a continuum frame. However, the way they influence the motion of a dislocation has not yet been computed, even in a approximate manner. An useful approximation that allows treating the boundary condition at the surface of a free-standing film consists of making use of the concept of image dislocation. Then, the critical stress for moving a dislocation in a free-standing film is the same as that of a capped layer of thickness twice that of the film. To date, models and dislocation dynamics (DD) simulations are available that involve several levels of approximation for the treatment of the dislocation/interface and dislocation/surface interactions [3–7]. For reasons that are not clearly understood, however, these models predict critical thicknesses that are systematically larger than the expected ones. The comparison with experiment is, in addition, made difficult because stresses have to be artificially introduced to replace the internal stresses and approximations have to be done to treat the image stresses. In the present work it is shown that it is now possible to fully account for the contribution of the various sources of internal stresses to the critical stress for the motion of a threading dislocation. This is performed numerically with the help of a hybrid code that combines a DD code for the treatment of the dislocation dynamics and a Finite Element (FE) code for the treatment of the boundary conditions. In what follows, several applications of this discrete-continuum model (DCM) to the study of dislocation motion in epitaxial layers are presented. The motion of a dislocation in a thin film is considered, including the image force and successively adding a misfit stress and an elastic incompatibility stress at the film/substrate interface.

Stability and Metastability in Semiconductor Strained-Layer Structures

1987 ◽  
Vol 103 ◽  
Author(s):  
Brian W. Dodson ◽  
I. J. Fritz ◽  
S. Thomas Picraux ◽  
Jeffrey Y. Tsao
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Structural Relaxation ◽  
Strain Relaxation ◽  
Dislocation Dynamics ◽  
Strained Layer ◽  
Stability Properties ◽  
Mismatch Strain ◽  
Layer Structures ◽  
Standard Models

ABSTRACTThe physics governing stability properties and relaxation of mismatch strain in semiconductor strained-layer structures is reviewed. Experimental data on stability and rates of strain relaxation are examined. We conclude that essentially all observations on structural relaxation of semiconductor strained-layer structures can be explained by standard models of plastic deformation adapted to the special conditions controlling dislocation dynamics in these structures.

Composition uniformity and large degree of strain relaxation in MBE-grown thick GeSn epitaxial layers, containing 16% Sn

2021 ◽  
Vol 54 (18) ◽  
pp. 185105
Author(s):  
Jaswant Rathore ◽  
Alisha Nanwani ◽  
Samik Mukherjee ◽  
Sudipta Das ◽  
Oussama Moutanabbir ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Large Degree ◽  
Epitaxial Layers
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