An assessment of the roles of climb and glide in misfit strain relief

1994 ◽  
Vol 75 (2) ◽  
pp. 872-878 ◽  
Author(s):  
W. A. Jesser ◽  
J. H. van der Merwe
Keyword(s):  
Misfit Strain ◽  
Strain Relief

Structural and electronic properties of defects in semiconductors

1995 ◽  
Vol 53 ◽  
pp. 4-5
Author(s):  
J.L. Batstone
Keyword(s):  
Semiconductor Device ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Extended Defects ◽  
Transmission Electron ◽  
Semiconductor Thin Films ◽  
Wide Range ◽  
Metal Organic ◽  
Film Substrate

The development of growth techniques such as metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy during the last fifteen years has resulted in the growth of high quality epitaxial semiconductor thin films for the semiconductor device industry. The III-V and II-VI semiconductors exhibit a wide range of fundamental band gap energies, enabling the fabrication of sophisticated optoelectronic devices such as lasers and electroluminescent displays. However, the radiative efficiency of such devices is strongly affected by the presence of optically and electrically active defects within the epitaxial layer; thus an understanding of factors influencing the defect densities is required.Extended defects such as dislocations, twins, stacking faults and grain boundaries can occur during epitaxial growth to relieve the misfit strain that builds up. Such defects can nucleate either at surfaces or thin film/substrate interfaces and the growth and nucleation events can be determined by in situ transmission electron microscopy (TEM).

Epitaxial Growth in Dislocation-Free Strained Alloy Films

2002 ◽  
Vol 715 ◽  
Author(s):  
Zhi-Feng Huang ◽  
Rashmi C. Desai
Keyword(s):  
Deposition Rate ◽  
Elastic Moduli ◽  
Composition Dependence ◽  
Critical Thickness ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Joint Stability ◽  
Alloy Films ◽  
The Stability ◽  
Stability Results

AbstractThe morphological and compositional instabilities in the heteroepitaxial strained alloy films have attracted intense interest from both experimentalists and theorists. To understand the mechanisms and properties for the generation of instabilities, we have developed a nonequilibrium, continuum model for the dislocation-free and coherent film systems. The early evolution processes of surface pro.les for both growing and postdeposition (non-growing) thin alloy films are studied through a linear stability analysis. We consider the coupling between top surface of the film and the underlying bulk, as well as the combination and interplay of different elastic effects. These e.ects are caused by filmsubstrate lattice misfit, composition dependence of film lattice constant (compositional stress), and composition dependence of both Young's and shear elastic moduli. The interplay of these factors as well as the growth temperature and deposition rate leads to rich and complicated stability results. For both the growing.lm and non-growing alloy free surface, we determine the stability conditions and diagrams for the system. These show the joint stability or instability for film morphology and compositional pro.les, as well as the asymmetry between tensile and compressive layers. The kinetic critical thickness for the onset of instability during.lm growth is also calculated, and its scaling behavior with respect to misfit strain and deposition rate determined. Our results have implications for real alloy growth systems such as SiGe and InGaAs, which agree with qualitative trends seen in recent experimental observations.

CHARACTERIZATION OF AL-6%MG MODIFIED WITH 0.15% OF ZR ALLOY AND SUBMITTED STRAIN RELIEF THE 400°C/1H

2019 ◽  
Author(s):  
Brenda Daniel ◽  
BEATRIZ SEABRA MELO ◽  
Marcus Vinícius Wanderley ◽  
Ricardo França ◽  
Natália Luiza Abucater Brum ◽  
...  
Keyword(s):  
Strain Relief ◽  
Zr Alloy

Results of Applying the Method of Visual Fatigue Prevention Using Low-Intensity Laser Radiation

2020 ◽  
pp. 56-59
Author(s):  
NYu Mal’kova ◽  
MD Petrova
Keyword(s):  
Laser Radiation ◽  
Work Experience ◽  
Study Groups ◽  
Light Sensitivity ◽  
Control Group ◽  
Sensitivity Threshold ◽  
Visual Fatigue ◽  
Strain Relief ◽  
Visual Stress ◽  
Stress At Work

Summary. Introduction: Visual fatigue is caused by changes in the muscular apparatus and retina of the eye and is characterized by deterioration in their functional activity. Along with an increase in work experience and age, workplace visual stress promotes the loss of performance. Known methods of visual fatigue prevention and eye strain relief are ineffective. In this regard, a technique of relieving visual fatigue using scattered low-level red laser radiation was developed and patented. The purpose of our study was a retrospective evaluation of effectiveness of the visual fatigue reduction technique. Materials and methods: We examined two groups of women (PC operators and jewellers) aged 43–57 years experiencing visual stress at work and practicing the method under study over the previous 20 years. The state of daylight vision was assessed by adaptation time. Results: A five-day testing of the method of visual fatigue relief showed stabilization of the light sensitivity threshold throughout the work shift. Over the 20-year period, the female workers had had no complaints of eye strain, burning or lacrimation. Objective studies of the functional state of the organ of sight showed that the light sensitivity threshold during the working day in two study groups was significantly lower than that in the control group with no preventive measures taken. Conclusions: We established that using the technique of eye strain relief based on a two-minute binocular exposure to red laser radiation with the power density of 2×10–7 W/cm2, a 5-day course every six months over the period of 20 years, helped retain retinal activity in terms of light sensitivity, thus preventing visual fatigue.

scholarly journals Misfit Strain Relaxation of Ferroelectric PbTiO3/LaAlO3 (111) Thin Film System

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Y. B. Xu ◽  
Y. L. Tang ◽  
Y. L. Zhu ◽  
Y. Liu ◽  
S. Li ◽  
...  
Keyword(s):  
Thin Film ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
Film System ◽  
Thin Film System

scholarly journals Thin film bi-epitaxy and transition characteristics of TiO2/TiN buffered VO2 on Si(100) substrates

MRS Advances ◽  
2016 ◽  
Vol 1 (37) ◽  
pp. 2635-2640 ◽  
Author(s):  
Adele Moatti ◽  
Reza Bayati ◽  
Srinivasa Rao Singamaneni ◽  
Jagdish Narayan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Magnetic Properties ◽  
Frequency Factor ◽  
Misfit Strain ◽  
Buffer Layers ◽  
Intrinsic Defects ◽  
Domain Matching Epitaxy ◽  
Out Of Plane

ABSTRACTBi-epitaxial VO2 thin films with [011] out-of-plane orientation were integrated with Si(100) substrates through TiO2/TiN buffer layers. At the first step, TiN is grown epitaxially on Si(100), where a cube-on-cube epitaxy is achieved. Then, TiN was oxidized in-situ ending up having epitaxial r-TiO2. Finally, VO2 was deposited on top of TiO2. The alignment across the interfaces was stablished as VO2(011)║TiO2(110)║TiN(100)║Si(100) and VO2(110) /VO2(010)║TiO2(011)║TiN(112)║Si(112). The inter-planar spacing of VO2(010) and TiO2(011) equal to 2.26 and 2.50 Å, respectively. This results in a 9.78% tensile misfit strain in VO2(010) lattice which relaxes through 9/10 alteration domains with a frequency factor of 0.5, according to the domain matching epitaxy paradigm. Also, the inter-planar spacing of VO2(011) and TiO2(011) equals to 3.19 and 2.50 Å, respectively. This results in a 27.6% compressive misfit strain in VO2(011) lattice which relaxes through 3/4 alteration domains with a frequency factor of 0.57. We studied semiconductor to metal transition characteristics of VO2/TiO2/TiN/Si heterostructures and established a correlation between intrinsic defects and magnetic properties.

Dislocation Nucleation and Growth in MOCVD GaN/AlN Films on Stepped and Step-free 4H-SiC Mesa Substrates

2008 ◽  
Vol 1090 ◽  
Author(s):  
Mark E. Twigg ◽  
Yoosuf N. Picard ◽  
Nabil D. Bassim ◽  
Joshua D. Caldwell ◽  
Michael A. Mastro ◽  
...  
Keyword(s):  
Dominant Role ◽  
High Stress ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Nucleation And Growth ◽  
Dislocation Nucleation ◽  
Threading Dislocations ◽  
Surface Steps ◽  
Half Loop ◽  
Edge Dislocations

AbstractUsing transmission electron microscopy, we have analyzed dislocations in AlN nucleation layers and GaN films grown by metallorganic chemical vapor deposition (MOCVD) on the (0001) surface of epitaxially-grown 4H-SiC mesas with and without steps. For 4H-SiC substrates free of SiC surface steps, half-loop nucleation and glide parallel to the AlN/SiC interfacial plane play the dominant role in strain relief, with no mechanism for generating threading dislocations. In contrast, 4H-SiC mesa surfaces with steps give rise to regions of high stress at the heteroepitaxial interface, thereby providing an environment conducive to the nucleation and growth of threading dislocations, which act to accommodate misfit strain by the tilting of threading edge dislocations.

Domain evolution of tetragonal Pb(ZrxTi1−x) O3 piezoelectric thin films on SrTiO3 (100) surfaces: combined effects of misfit strain and Zr/Ti ratio

2014 ◽  
Vol 2 (29) ◽  
pp. 5836-5841 ◽  
Author(s):  
Qi Yu ◽  
Jing-Feng Li ◽  
Fang-Yuan Zhu ◽  
Jiangyu Li
Keyword(s):  
Thin Films ◽  
Misfit Strain ◽  
Epitaxial Thin Films ◽  
Combined Effects ◽  
Piezoelectric Thin Films ◽  
Domain Evolution ◽  
Ferroelectric Domains ◽  
Substrate Constraint

The ferroelectric domains of tetragonal Pb(ZrxTi1−x)O3 epitaxial thin films have been studied comprehensively to reveal their piezoelectric responses under substrate constraint.

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