Mechanisms and Kinetics of Misfit Dislocation Formation in Heteroepitaxial Thin Films

1990 ◽  
Vol 188 ◽  
Author(s):  
W. D. Nix ◽  
D. B. Noble ◽  
J. F. Turlo
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Dislocation Motion ◽  
Dislocation Nucleation ◽  
Dislocation Segment ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Film Substrate ◽  
Kinetics Of ◽  
Dislocation Formation

ABSTRACTThe mechanisms and kinetics of forming misfit dislocations in heteroepitaxial films are studied. The critical thickness for misfit dislocation formation can be found by considering the incremental extension of a misfit dislocation by the movement of a “threading” dislocation segment that extends from the film/substrate interface to the free surface of the film. This same mechanism allows one to examine the kinetics of dislocation motion and to illuminate the importance of dislocation nucleation and multiplication in strain relaxation. The effects of unstrained epitaxial capping layers on these processes are also considered. The major effects of such capping layers are to inhibit dislocation nucleation and multiplication. The effect of the capping layer on the velocity of the “threading” dislocation is shown to be small by comparison.A new substrate curvature technique for measuring the strain and studying the kinetics of strain relaxation in heteroepitaxial films is also briefly described.

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.

Kinetics of strain relaxation through misfit dislocation formation in InAs/GaAs(111)A heteroepitaxy

1999 ◽  
Vol 441 (2-3) ◽  
pp. L911-L916 ◽  
Author(s):  
Luis A. Zepeda-Ruiz ◽  
Brett Z. Nosho ◽  
Rodney I. Pelzel ◽  
W.Henry Weinberg ◽  
Dimitrios Maroudas
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Kinetics Of ◽  
Dislocation Formation

A Misfit Dislocation Blocking Mechanism in Continuous InGaAs Layers Grown on Patterned GaAs

1993 ◽  
Vol 308 ◽  
Author(s):  
G. Patrick Watson ◽  
Dieter G. Ast ◽  
Timothy J. Anderson ◽  
Balu Pathangey
Keyword(s):  
Misfit Dislocation ◽  
Energy Cost ◽  
Dislocation Segment ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Blocking Mechanism

ABSTRACTPrevious work showed that misfit dislocations were blocked at trench walls in a unique way in InGaAs strained layers grown on GaAs that was patterned and etched to form a series of mesas separated by trenches. A model is developed to explain the behavior of misfit dislocations in this material. The energy cost of extending the threading dislocation segment, which accompanies a misfit dislocation during glide, can impede the motion of these defects if the trench walls are steep enough.

“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.

Initial Strain Relaxation in S0.91Ge0.09/Si Superlattice Structures via Misfit-Dislocations

1999 ◽  
Vol 570 ◽  
Author(s):  
J. Leininger ◽  
G. D. U'ren ◽  
M. S. Goorsky
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
High Vacuum ◽  
Average Density ◽  
Dislocation Nucleation ◽  
Ultra High Vacuum ◽  
Initial Strain ◽  
Homogeneous Distribution ◽  
Misfit Dislocations ◽  
Dislocation Sources

ABSTRACTWe addressed the initial strain relaxation of symmetric 95 Å period Si0.91Ge0.09/Si heterostructures grown by ultra-high vacuum chemical vapor deposition on vicinal substrates miscut 2.04° from (001) in a direction 36° from a [110]. Double-axis x-ray topography revealed misfit-dislocation sources in the as-grown samples with an average density of about 60 cm−2, although the distribution of these sites was not homogeneous. The progression of dislocation nucleation and growth was observed during subsequent rapid thermal annealing (800°C, 20s-320s). Physical heterogeneities were identified as dislocation sources, and they gave rise to orthogonal misfit dislocation bundles, which on a macroscopic scale resemble crosses. Upon longer annealing, a more homogeneous distribution of defects was observed without measurable relaxation. These original defects did propagate; however, they did not spur a cross-slip multiplication sequence.

Relationship between misfit-dislocation formation and initial threading-dislocation density in GaInN/GaN heterostructures

2015 ◽  
Vol 54 (11) ◽  
pp. 115501 ◽  
Author(s):  
Motoaki Iwaya ◽  
Taiji Yamamoto ◽  
Daisuke Iida ◽  
Yasunari Kondo ◽  
Mihoko Sowa ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Misfit Dislocation ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Dislocation Formation

A New Dislocation-Dynamics Model and Its Application in Thin Film-Substrate Systems

2005 ◽  
Vol 875 ◽  
Author(s):  
E.H. Tan ◽  
L.Z. Sun
Keyword(s):  
Thin Films ◽  
Mechanical Performance ◽  
Dislocation Motion ◽  
Dislocation Dynamics ◽  
Dislocation Segment ◽  
Dislocation Loops ◽  
Dynamics Model ◽  
Proposed Model ◽  
Simulation Results ◽  
Film Substrate

AbstractBased on the physical background, a new dislocation dynamics model fully incorporating the interaction among differential dislocation segments is developed to simulate 3D dislocation motion in crystals. As the numerical simulation results demonstrate, this new model completely solves the long-standing problem that simulation results are heavily dependent on dislocation-segment lengths in the classical dislocation dynamics theory. The proposed model is applied to simulate the effect of dislocations on the mechanical performance of thin films. The interactions among the dislocation loops, free surface and interfaces are rigorously computed by a decomposition method. This framework can be used to simulate how a surface loop evolves into two threading dislocations and to determine the critical thickness of thin films. Furthermore, the relationship between the film thickness and yield strength is established and compared with the conventional Hall-Petch relation.

Transition From Inclined to In-Plane 60° Misfit Dislocations in a Diffuse Interface

1993 ◽  
Vol 319 ◽  
Author(s):  
X. J. Ning ◽  
P. Pirouz
Keyword(s):  
Strain Relaxation ◽  
Classical Model ◽  
Diffuse Interface ◽  
Misfit Dislocations ◽  
Dislocation Loops ◽  
Boron Diffusion ◽  
Plan View ◽  
Transmission Electron ◽  
Mechanisms Of Formation ◽  
Film Substrate

AbstractDespite tremendous activity during the last few decades in the study of strain relaxation in thin films grown on substrates of a dissimilar material, there are still a number of problems which are unresolved. One of these is the nature of misfit dislocations forming at the film/substrate interface: depending on the misfit, the dislocations constituting the interfacial network have predominantly either in-plane or inclined Burgers vectors. While, the mechanisms of formation of misfit dislocations with inclined Burgers vectors are reasonably well understood, this is not the case for in-plane misfit dislocations whose formation mechanism is still controversial. In this paper, misfit dislocations generated to relax the strains caused by diffusion of boron into silicon have been investigated by plan-view and crosssectional transmission electron microscopy. The study of different stages of boron diffusion shows that, as in the classical model of Matthews, dislocation loops are initially generated at the epilayer surface. Subsequently the threading segments expand laterally and lay down a segment of misfit dislocation at the diffuse interface. The Burgers vector of the dislocation loop is inclined with respect to the interface and thus the initial misfit dislocations are not very efficient. However, as the diffusion proceeds, non-parallel dislocations interact and give rise to product segments that have parallel Burgers vectors. Based on the observations, a model is presented to elucidate the details of these interactions and the formation of more efficient misfit dislocations from the less-efficient inclined ones.

Effect of C and Ge Concentration On The Thermal Stability of RTCVD Grown Si1-x-yGexCy Alloys

1997 ◽  
Vol 470 ◽  
Author(s):  
Patricia Warren ◽  
Stephane Retzmanick ◽  
Martin Gotza ◽  
Marc Begems
Keyword(s):  
Lattice Constant ◽  
Strain Relaxation ◽  
Mechanical Strain ◽  
Chemical Vapor ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Cubic Silicon Carbide ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTSi / Si1-x-yGexCy / Si heterostructures containing up to 17 at.% Ge and 1.9 at.% C were grown on (001) silicon by low pressure Rapid Thermal Chemical Vapor Deposition, using a mixture of silane, germane and methylsilane, diluted in hydrogen. The samples were then annealed in a Rapid Thermal Processing furnace, under an atmospheric pressure of nitrogen, at temperatures ranging from 900 to 1130 °C.The samples were characterized using infrared spectroscopy and x-ray diffraction. SIMS profiling and TEM observation were performed on some of the samples.Substitutional C gradually disappeared, either precipitating out to form cubic silicon carbide (β-SiC), or simply vanishing into interstitial positions. In any case, the in-plane lattice constant remained constant after annealing, indicating that there was no mechanical strain relaxation by formation of misfit dislocations. The perpendicular lattice constant increased due to the decrease in substitutional C concentration, as well as it decreased due to the germanium out-diffusion. This variation of the strain during annealing was modeled, and allowed the determination of the kinetics of the substitutional carbon disappearance. The same behavior was observed for all samples. Indeed, the Cs disappearance rate was always increased for samples with higher initial Ge and C concentrations. The kinetics of this precipitation was found in very good agreement with previous published results.

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