Strain relaxation in ultrathin films: A modified theory of misfit-dislocation energetics

1993 ◽  
Vol 47 (20) ◽  
pp. 13730-13736 ◽  
Author(s):  
A. P. Payne ◽  
B. M. Lairson ◽  
B. M. Clemens
Keyword(s):  
Misfit Dislocation ◽  
Ultrathin Films ◽  
Strain Relaxation ◽  
Modified Theory

Development of Cross-Hatch Morphology During Growth of Lattice Mismatched Layers

2001 ◽  
Vol 673 ◽  
Author(s):  
A. Maxwell Andrews ◽  
J.S. Speck ◽  
A.E. Romanov ◽  
M. Bobeth ◽  
W. Pompe
Keyword(s):  
Misfit Dislocation ◽  
Film Growth ◽  
Strain Relaxation ◽  
Dislocation Generation ◽  
Force Microscopy ◽  
Step Flow ◽  
Atomic Force ◽  
Subsequent Step ◽  
Step Flow Growth ◽  
Lateral Scale

ABSTRACTAn approach is developed for understanding the cross-hatch morphology in lattice mismatched heteroepitaxial film growth. It is demonstrated that both strain relaxation associated with misfit dislocation formation and subsequent step elimination (e.g. by step-flow growth) are responsible for the appearance of nanoscopic surface height undulations (0.1-10 nm) on a mesoscopic (∼100 nm) lateral scale. The results of Monte Carlo simulations for dislocation- assisted strain relaxation and subsequent film growth predict the development of cross-hatch patterns with a characteristic surface undulation magnitude ∼50 Å in an approximately 70% strain relaxed In0.25Ga0.75As layers. The model is supported by atomic force microscopy (AFM) observations of cross-hatch morphology in the same composition samples grown well beyond the critical thickness for misfit dislocation generation.

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.

An In-Situ Study of the Segregation and the Strain Relaxation During Growth of Gold and Nickel Ultrathin Films

1999 ◽  
Vol 562 ◽  
Author(s):  
S. Labat ◽  
P. Gergaud ◽  
O. Thomas ◽  
B. Gilles ◽  
A. Marty
Keyword(s):  
Ultrathin Films ◽  
Strain Relaxation ◽  
High Energy ◽  
Stress And Strain ◽  
High Energy Electron ◽  
In Situ Study ◽  
Real Time Measurement ◽  
Ultrathin Layers ◽  
Large Asymmetry

ABSTRACTWe report on in-situ real time measurement of both stress and strain during growth of ultrathin layers, with submonolayer sensitivity. The in-plane parameter is measured by Reflection High Energy Electron Diffraction (RHEED) and the stress is determined via the measurement of the curvature. The system studied is Au/Ni (i.e. Au on Ni and Ni on Au). We have evidenced a large asymmetry in the two different growths: Au (on Ni) shows a progressive elastic strain relaxation whereas Ni (on Au) exhibits a strong interplay between the stress and the interfacial mixing.

Control of misfit dislocation glide plane distribution during strain relaxation of CuPt-ordered GaInAs and GaInP

2012 ◽  
Vol 112 (2) ◽  
pp. 023520 ◽  
Author(s):  
R. M. France ◽  
W. E. McMahon ◽  
A. G. Norman ◽  
J. F. Geisz ◽  
M. J. Romero
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Dislocation Glide ◽  
Plane Distribution

Strain Relaxation Mechanisms in He+-Implanted and Annealed Si1−xGex Layers on Si(001) Substrates

2001 ◽  
Vol 686 ◽  
Author(s):  
S.H. Christiansen ◽  
P.M. Mooney ◽  
J.O. Chu ◽  
A. Grill
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Three Dimensional ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
Transmission Electron ◽  
Microscopy Techniques

AbstractStrain relaxation in He+-implanted and annealed Si(001)/Si1−xGex heterostructures was investigated using transmission electron microscopy techniques and x-ray diffraction. Depending on the implant conditions, bubbles and/or platelets form below the Si/Si1−xGex interface upon annealing and act as nucleation sources for dislocation loops. The dislocation loops extend to the interface and form a misfit dislocation network there, resulting in relaxation of 30-80% of the strain in layers as thin as 100-300 nm. When bubbles form close to the interface, dislocations nucleate by a climb loop mechanism. When smaller bubbles form deeper in the Si substrate an irregular three-dimensional dislocation network forms below the interface resulting in an irregular misfit dislocation network at the interface. When platelets form deeper in the Si substrate, prismatic punching of dislocation loops is observed and dislocation reactions of misfit dislocations at the interface result in Lomer dislocation formation.

A Theoretical Calculation of Misfit Dislocation and Strain Relaxation in Step-graded InxGa 1-x N/GaN Layers

2011 ◽  
Vol 403-408 ◽  
pp. 456-460 ◽  
Author(s):  
Md. Arafat Hossain ◽  
Md. Rafiqul Islam
Keyword(s):  
Theoretical Calculation ◽  
Layer Thickness ◽  
Misfit Dislocation ◽  
Residual Strain ◽  
Critical Thickness ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Uniform Layer ◽  
Dislocation Energy

This paper presents a theoretical calculation of misfit dislocation and strain relaxation in compositionally step graded InxGa1-xN grown on GaN using the total dislocation energy at each interface. The results also compared with uniform layer of In0.17Ga0.83N and In0.14Ga0.86N grown differently on GaN. Due to having residual strain and a step increase in indium composition a lower misfit strain in upper layers and hence larger critical thickness at each interface has been reported. These effects significantly reduced the misfit dislocations from 2.6×105cm-1to 9.5×104cm-1in step graded In0.14Ga0.86N(500nm)/In0.09Ga0.91N(100nm)/In0.05Ga0.95N(100nm)/GaN layers instead of a uniform In0.14Ga0.86N(700nm)/GaN. A small residual strain of 0.0007 after 700 nm graded layer thickness has been reported with 87.04% strain relaxation.

Strain Relaxation at Low Misfits: Dislocation Injection vs. Surface Roughening

1995 ◽  
Vol 399 ◽  
Author(s):  
D.D. Perovic ◽  
B. Bahierathan ◽  
D.C. Houghton ◽  
H. Lafontaine ◽  
J.-M. Baribeau
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
Theoretical Description ◽  
Dislocation Nucleation ◽  
Surface Roughening ◽  
X Ray Diffraction ◽  
Dislocation Generation ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTTwo competing strain relaxation mechanisms, namely misfit dislocation generation and surface roughening, have been extensively studied using the GexSi1-x/Si (x< 0.5) system as an example. A predictive model has been developed which accurately describes the nature of misfit dislocation nucleation and growth under non-equilibrium conditions. Using optical and electron microscopy, coupled with a refined theoretical description of dislocation nucleation, it is shown that strain relieving dislocations are readily generated at low misfits with a characteristic activation energy barrier regardless of the growth technique employed (i.e. MBE, RTCVD and UHVCVD). Secondly we have studied the alternative elastic strain relaxation mechanism involving surface undulation; x-ray diffraction, electron and atomic force microscopy have been used to characterize GexSi1-x/Si (x<0.5) structures grown by UHVCVD and MBE at relatively higher temperatures. A theoretical model has been used to model the critical thickness for surface wave generation. The conditions governing the interplay between dislocation formation and surface buckling are described in terms of a "morphological instability diagram".

Observations on the Mechanics of Strained Epitaxial Island Growth

1995 ◽  
Vol 399 ◽  
Author(s):  
L. B. Freund ◽  
H. T. Johnson ◽  
R. V. Kukta
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Energy ◽  
Aspect Ratio ◽  
Misfit Dislocation ◽  
Strain Distribution ◽  
Strain Relaxation ◽  
Lattice Parameter ◽  
Island Growth ◽  
Numerical Finite Element

ABSTRACTAn epitaxial material island which has a lattice parameter differing by a small amount for that of its substrate is considered within the framework of continuum mechanics. The strain distribution in the island is determined for a range of aspect ratio, taking into account the compliance of the substrate. It is demonstrated that the total free energy of a strained island is minimum for some value of aspect ratio, and that this value depends on the volume of the island. To consider strain relaxation, the nucleation of a dislocation at the edge of a strained island is examined and the equilibrium aspect ratio of a dislocated island is computed. In particular, it is shown that an island can reduce its free energy by reducing its aspect ratio and, simultaneously, forming an interface misfit dislocation. The simulations are based on the numerical finite element method.

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