Equilibrium strain and dislocation density in exponentially graded Si1−xGex/Si (001)

2010 ◽  
Vol 108 (11) ◽  
pp. 113525 ◽  
Author(s):  
B. Bertoli ◽  
D. Sidoti ◽  
S. Xhurxhi ◽  
T. Kujofsa ◽  
S. Cheruku ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Equilibrium Strain ◽  
Exponentially Graded

Equilibrium Strain and Dislocation Density in Nitride Based Heterostructures

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450009
Author(s):  
Johanna E. Raphael ◽  
Brandon Bertoli ◽  
John E. Ayers
Keyword(s):  
Crystal Structure ◽  
Dislocation Density ◽  
Misfit Dislocation ◽  
Energy Minimization ◽  
Computational Approach ◽  
Critical Layer Thickness ◽  
Density Profiles ◽  
Zinc Blende ◽  
Equilibrium Strain

This work presents a computational approach for the determination of equilibrium strain and dislocation density in nitride-based heterostructures. Verification of this approach is demonstrated in the calculation of critical layer thickness for In x Ga 1-x N / GaN (0001) as compared to other work. The present modeling approach can also be applied to heterostructures of varying compositional profiles and structure. To demonstrate this, we studied the equilibrium strain and misfit dislocation density profiles for metamorphic In x Ga 1-x N / GaN (0001) heterostructures containing uniform layers on top of linearly-graded buffers. These structures were also compared to similar arsenide-based heterostructures involving In x Ga 1-x As / GaAs (001) with the zinc blende crystal structure. The generalized energy minimization modeling tool presented here can be readily extended to arbitrarily graded nitride heterostructures with polar, semi-polar, or non-polar orientations.

Threading Dislocation Densities in Mismatched Heteroepitaxial (001) Semiconductors

1990 ◽  
Vol 209 ◽  
Author(s):  
J. E. Ayers ◽  
S.K. Ghandhi ◽  
L. J. Schowalter
Keyword(s):  
Dislocation Density ◽  
Film Thickness ◽  
Thickness Dependence ◽  
Threading Dislocation ◽  
Gaas On Si ◽  
Dislocation Densities ◽  
Threading Dislocation Density ◽  
Heteroepitaxial Layers ◽  
Equilibrium Strain ◽  
Good Agreement

ABSTRACTIn this paper we propose a theory which accounts for the thickness dependence of threading dislocation densities in mismatched heteroepitaxial (001) semiconductors. This theory predicts that, for thick, planar, highly-mismatched heteroepitaxial layers with equilibrium strain, the threading dislocation density should be proportional to f/h, where f is thelattice mismatch and h is the film thickness. These predictions are in good agreement with experimental resultsin the GaAs on Si(001) system.

Observations of dislocation interactions with recrystallized grain boundaries

1988 ◽  
Vol 46 ◽  
pp. 628-629
Author(s):  
C. W. Price
Keyword(s):  
Dislocation Density ◽  
Grain Boundary ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Dislocation Structure ◽  
Hot Deformation ◽  
Static Recrystallization ◽  
High Dislocation Density ◽  
High Angle ◽  
Dislocation Interactions

Little evidence exists on the interaction of individual dislocations with recrystallized grain boundaries, primarily because of the severely overlapping contrast of the high dislocation density usually present during recrystallization. Interesting evidence of such interaction, Fig. 1, was discovered during examination of some old work on the hot deformation of Al-4.64 Cu. The specimen was deformed in a programmable thermomechanical instrument at 527 C and a strain rate of 25 cm/cm/s to a strain of 0.7. Static recrystallization occurred during a post anneal of 23 s also at 527 C. The figure shows evidence of dissociation of a subboundary at an intersection with a recrystallized high-angle grain boundary. At least one set of dislocations appears to be out of contrast in Fig. 1, and a grainboundary precipitate also is visible. Unfortunately, only subgrain sizes were of interest at the time the micrograph was recorded, and no attempt was made to analyze the dislocation structure.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

DIFFRACTION ANALYSIS OF DEFORMED METALS: Theory, Methods, Programs

2019 ◽  
Author(s):  
Faina Satdarova
Keyword(s):  
Experimental Design ◽  
Dislocation Density ◽  
Mathematical Models ◽  
Diffraction Analysis ◽  
Experimental Research ◽  
Russian Federation ◽  
Statistical Estimation ◽  
X Rays ◽  
National University ◽  
The Russian Federation

General analysis of the distribution of crystals orientation and dislocation density in the polycrystalline system is presented. Recovered information in diffraction of X-rays adopting is new to structure states of polycrystal. Shear phase transformations in metals — at the macroscopic and microscopic levels — become a clear process. Visualizing the advances is produced by program included in package delivered. Mathematical models developing, experimental design, optimal statistical estimation, simulation the system under study and evolution process on loading serves as instrumentation. To reduce advanced methods to research and studies problem-oriented software will promote when installed. Automation programs passed a testing in the National University of Science and Technology “MISIS” (The Russian Federation, Moscow). You score an advantage in theoretical and experimental research in the field of physics of metals.

Low dislocation density AlN on sapphire prepared by double sputtering and annealing

2020 ◽  
Vol 13 (9) ◽  
pp. 095501
Author(s):  
Ding Wang ◽  
Kenjiro Uesugi ◽  
Shiyu Xiao ◽  
Kenji Norimatsu ◽  
Hideto Miyake
Keyword(s):  
Dislocation Density ◽  
Low Dislocation Density

ВЛИЯНИЕ ТВЕРДОФАЗНОЙ РЕКРИСТАЛЛИЗАЦИИ С ДВОЙНОЙ ИМПЛАНТАЦИЕЙ НА ПЛОТНОСТЬ СТРУКТУРНЫХ ДЕФЕКТОВ В УЛЬТРАТОНКИХ СЛОЯХ КРЕМНИЯ НА САПФИРЕ

2020 ◽  
Vol 96 (3s) ◽  
pp. 154-159
Author(s):  
Н.Н. Егоров ◽  
С.А. Голубков ◽  
С.Д. Федотов ◽  
В.Н. Стаценко ◽  
А.А. Романов ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Solid Phase ◽  
Modern Method ◽  
Structural Defects ◽  
Structural Quality ◽  
Mos Transistors ◽  
Ultrathin Layers ◽  
Heteroepitaxial Layers ◽  
Xrd And Tem

Высокая плотность структурных дефектов является основной проблемой при изготовлении электроники на гетероструктурах «кремний на сапфире» (КНС). Современный метод получения ультратонких структур КНС с помощью твердофазной эпитаксиальной рекристаллизации позволяет значительно снизить дефектность в гетероэпитаксиальном слое КНС. В данной работе ультратонкие (100 нм) слои КНС были получены путем рекристаллизации и утонения субмикронных (300 нм) слоев кремния на сапфире, обладающих различным структурным качеством. Плотность структурных дефектов в слоях КНС оценивалась с помощью рентгеноструктурного анализа и просвечивающей электронной микроскопии. Кривые качания от дифракционного отражения Si(400), полученные в ω-геометрии, продемонстрировали максимальную ширину на полувысоте пика не более 0,19-0,20° для ультратонких слоев КНС толщиной 100 нм. Формирование структурно совершенного субмикронного слоя КНС 300 нм на этапе газофазной эпитаксии обеспечивает существенное уменьшение плотности дислокаций в ультратонком кремнии на сапфире до значений ~1 • 104 см-1. Тестовые n-канальные МОП-транзисторы на ультратонких структурах КНС характеризовались подвижностью носителей в канале 725 см2 Вс-1. The high density of structural defects is the main problem on the way to the production of electronics on silicon-on-sapphire (SOS) heteroepitaxial wafers. The modern method of obtaining ultrathin SOS wafers is solid-phase epitaxial recrystallization which can significantly reduce the density of defects in the SOS heteroepitaxial layers. In the current work, ultrathin (100 nm) SOS layers were obtained by recrystallization and thinning of submicron (300 nm) SOS layers, which have various structural quality. The density of structural defects in the layers was estimated by using XRD and TEM. Full width at half maximum of rocking curves (ω-geometry) was no more than 0.19-0.20° for 100 nm ultra-thin SOS layers. The structural quality of 300 nm submicron SOS layers, which were obtained by CVD, depends on dislocation density in 100 nm ultrathin layers. The dislocation density in ultrathin SOS layers was reduced by ~1 • 104 cm-1 due to the utilization of the submicron SOS with good crystal quality. Test n-channel MOS transistors based on ultra-thin SOS wafers were characterized by electron mobility in the channel 725 cm2 V-1 s-1.

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