scholarly journals Theoretical consideration of misfit dislocation nucleation by partial dislocations in [001] strained‐layer heterostructures

1993 ◽  
Vol 74 (2) ◽  
pp. 925-930 ◽  
Author(s):  
J. Zou ◽  
D. J. H. Cockayne
Keyword(s):  
Misfit Dislocation ◽  
Theoretical Consideration ◽  
Dislocation Nucleation ◽  
Strained Layer ◽  
Partial Dislocations

“Barrierless” Misfit Dislocation Nucleation in SiGe/Si Strained Layer Epitaxy

1992 ◽  
Vol 263 ◽  
Author(s):  
D.D. Perovic ◽  
D.C. Houghton
Keyword(s):  
Activation Energy ◽  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Dislocation Nucleation ◽  
Theoretical Treatment ◽  
Misfit Dislocations ◽  
Plan View ◽  
Strained Layer ◽  
Wide Range ◽  
Peierls Barrier

ABSTRACTThe study of the critical thickness/strain phenomenon inherent in metastable, layered heterostructures has led to the development of several models which describe elastic strain relaxation. Hitherto, the nucleation of misfit dislocations required for coherency breakdown is the least well understood aspect of strain relaxation, due to the paucity of experimental data. Moreover, existing theoretical calculations predict relatively large activation energy barriers (>10 eV) for misfit dislocation nucleation in relatively low misfit (<2%) systems. In this work it will be shown that the nucleation of misfit dislocations can occur spontaneously demonstrating a vanishingly small activation energy barrier. Specifically, experimental studies of a wide range of GexSi1−x/Si (x< 0.5) hetero-structures, grown by MBE and CVD techniques, have provided quantitative data from bulk specimens on the observed misfit dislocation nucleation rate and activation energy using large-area diagnostic techniques (eg. chemical etching/Nomarski microscopy). In parallel, the strained layer microstructure was studied in detail using crosssectional and plan-view electron microscopy in order to identify a new dislocation nucleation mechanism, the ‘double half-loop’ source. From the combined macroscopic and microscopic analyses, a theoretical treatment has been developed based on nucleation stress and energy criteria which predicts a “barrierless” nucleation process exists even at low misfits (< 1%). Accordingly, the observed misfit dislocation nucleation event has been found both experimentally and theoretically to be rate-controlled solely by Peierls barrier dependent, glide-activated processes with activation energies of ∼2 eV.

Anisotropic misfit dislocation nucleation in two-dimensional grown InAs/GaAs(001) heterostructures

1998 ◽  
Vol 73 (8) ◽  
pp. 1074-1076 ◽  
Author(s):  
Achim Trampert ◽  
Klaus H. Ploog ◽  
Eric Tournié
Keyword(s):  
Misfit Dislocation ◽  
Dislocation Nucleation ◽  
Two Dimensional

Atomistic simulation for configuration evolution and energetic calculation of crack in body-centered-cubic iron

2006 ◽  
Vol 21 (10) ◽  
pp. 2542-2549 ◽  
Author(s):  
Li-Xia Cao ◽  
Chong-Yu Wang
Keyword(s):  
Low Temperatures ◽  
Crack Tip ◽  
Dislocation Nucleation ◽  
Effect Of Temperature ◽  
Body Centered Cubic ◽  
Partial Dislocations ◽  
Higher Temperature ◽  
Crack Blunting ◽  
Increasing Temperature ◽  
Extended Dislocation

The molecular dynamics method has been used to simulate mode I cracking in body-centered-cubic iron. Close attention has been paid to the process of the atomic configuration evolution of the cracks. The simulation shows that at low temperatures, partial dislocations are emitted before the initiation of crack propagation, subsequently forming the stacking faults or multilayer twins on {112} planes, and then brittle cleavage and extended dislocation nucleation are observed at the crack tip accompanied by twin extension. These results are in agreement with the experimental observation that twinning and fracture processes cooperate at low temperatures. Furthermore, an energetics analysis has been made on the deformation behavior observed at the crack tip. The effect of temperature on the fracture process is discussed. At the higher temperature, plastic deformation becomes easier, and crack blunting occurs. With increasing temperature, the fracture resistance increases, and the effect of the lattice trapping can be weakened by thermal activation.

Rapid Thermal Processing of Buried Sil−xGex Strained Layers; Photoluminescence Decay and Misfit Dislocation Generation.

1990 ◽  
Vol 198 ◽  
Author(s):  
D.C. Houghton ◽  
N.L. Rowell
Keyword(s):  
Quantum Wells ◽  
Misfit Dislocation ◽  
Thermal Processing ◽  
Internal Quantum Efficiency ◽  
Dislocation Nucleation ◽  
Multiple Quantum ◽  
Misfit Dislocations ◽  
Dislocation Generation ◽  
Strained Layers ◽  
Wide Range

ABSTRACTThe thermal constraints for device processing imposed by strain relaxation have been determined for a wide range of Si-Ge strained heterostructures. Misfit dislocation densities and glide velocities in uncapped Sil-xGex alloy layers, Sil-xGex single and multiple quantum wells have been measured using defect etching and TEM for a range of anneal temperatures (450°C-1000°C) and anneal times (5s-2000s). The decay of an intense photoluminescence peak (∼ 10% internal quantum efficiency ) from buried Si1-xGex strained layers has been correlated with the generation of misfit dislocations in adjacent Sil-xGex /Si interfaces. The misfit dislocation nucleation rate and glide velocity for all geometries and alloy compositions (0<x<0.25) were found to be thermally activated processes with activation energies of (2.5±0.2)eV and (2.3-0.65x)eV, respectively. The time-temperature regime available for thermal processing is mapped out as a function of dislocation density using a new kinetic model.

The Roles of Stress, Geometry and Orientation on Misfit Dislocations Kinetics and Energetics in Epitaxial Strained Layers.

1991 ◽  
Vol 239 ◽  
Author(s):  
R. Hull ◽  
J. C. Bean ◽  
F. Ross ◽  
D. Bahnck ◽  
L. J. Pencolas
Keyword(s):  
Misfit Dislocation ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Misfit Dislocations ◽  
Slip Systems ◽  
Strained Layers ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Strain Stress ◽  
Kinetics Of

ABSTRACTThe geometries, microstructures, energetics and kinetics of misfit dislocations as functions of surface orientation and the magnitude of strain/stress are investigated experimentally and theoretically. Examples are drawn from (100), (110) and (111) surfaces and from the GexSi1–x/Si and InxGa1–x/GaAs systems. It is shown that the misfit dislocation geometries and microstructures at lattice mismatch stresses < - 1GPa may in general be predicted by operation of the minimum magnitude Burgers vector slipping on the widest spaced planes. At stresses of the order several GPa, however, new dislocation systems may become operative with either modified Burgers vectors or slip systems. Dissociation of totál misfit dislocations into partial dislocations is found to play a crucial role in strain relaxation, on surfaces other than (100) under compressive stress.

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