Numerical study on the effect of additional resistive heating and crystal rotation on sapphire single crystals (Al2O3) grown by the Kyropoulos method

In order to control the impurity distribution and remove defects in a crystal grown in Czochralski growth for high quality crystals of silicon, it is necessary to study and control the melt-crystal interface shape, which plays an important role in control of the crystal quality. The melt-crystal interface interacts with and is determined by the convective thermal flow of the melt in the crucible. Application of magnetic field in the Czochralski system is an effective tool to control the convective thermal flow in the crucible. Therefore, the shape of the melt-crystal interface can be modified accordingly. Numerical study is performed in this paper to understand the effect of magnetic field on the interface deflection in Czochralski system. Comparisons have been carried out by computations for four arrangements of the magnetic field: without magnetic field, a vertical magnetic field and two types of cusp-shaped magnetic field. The velocity, pressure, thermal and electromagnetic fields are solved with adaptation of the mesh to the iteratively modified interface shape. The multi-block technique is applied to discretize the melt field in the crucible and the solid field of silicon crystal. The unknown shape of the melt-crystal interface is achieved by an iterative procedure. The computation results show that the magnetic fields have obvious effects on both the pattern and strength of the convective flow and the interface shape. Applying magnetic field in the Czochralski system, therefore, is an effective tool to control the quality of bulk crystal in Czochralski growth process.

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Numerical study of instability in a horizontal porous channel with bottom heating and forced horizontal flow

Physics of Fluids ◽

10.1063/1.869741 ◽

1998 ◽

Vol 10 (9) ◽

pp. 2198-2207 ◽

Cited By ~ 16

Author(s):

Françoise Dufour ◽

Marie-Christine Neel

Keyword(s):

Numerical Study ◽

Horizontal Flow ◽

Porous Channel ◽

Bottom Heating

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Correlation Between Crystal Rotation and Redundant Shear Strain in Rolled Single Crystals: A Crystal Plasticity FE Analysis

Acta Metallurgica Sinica (English Letters) ◽

10.1007/s40195-018-0859-5 ◽

2018 ◽

Vol 32 (4) ◽

pp. 452-460 ◽

Cited By ~ 1

Author(s):

Hui Wang ◽

Cheng Lu ◽

Kiet Tieu ◽

Yu Liu ◽

Rui Wang ◽

...

Keyword(s):

Shear Strain ◽

Single Crystals ◽

Crystal Plasticity ◽

Fe Analysis ◽

Crystal Rotation

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Simulation of Transport Phenomena and Interfacial Dynamics During Czochralski Growth of Oxide Crystals

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2008-62116 ◽

2008 ◽

Author(s):

Jyotirmay Banerjee ◽

K. Muralidhar

Keyword(s):

Melting Point ◽

Wall Temperature ◽

Growth Process ◽

Transport Phenomena ◽

Control Parameters ◽

Crystal Rotation ◽

Constant Diameter ◽

Oxide Crystals ◽

Crystal Interface

The quality of crystal grown in a Czochralski apparatus depends on a well organized flow and thermal field in the vicinity of the melt-crystal interface. A mathematical model that explores transport phenomena and the formation, evaluation and dynamics of the interface in a Czochralski apparatus is presented. The numerical formulation allows for the consideration of conduction in the crystal, conduction and convection in the melt and the gas phase, surface tension gradients, bulk and surface radiation and crystal rotation. Low temperature experiments using liquid crystal thermography have been conducted for validating the numerical codes. The control parameters for the Czochralski crystal growth process are crystal rotation, crucible wall and the enclosure wall temperature. Numerical simulations are carried out to establish the influence of these control parameters on the quality of oxide crystals grown in a Czochralski apparatus. Rare earth garnet YAG is considered as representative oxide material for the purpose of modeling and numerical simulation. Quantities of interest are the shape of the melt-crystal interface and the variation of pull velocity for the growth of constant diameter crystal. Steady state simulations carried out for the full Czochralski domain reveals the possibility of superheating of the crystal beyond its melting point, thus leading to the grown crystal returning to the melt. Similarly, the possibility of subcooling of the melt below the melting point of YAG at locations away from the crystal edge is indicated. The quasi-steady simulation of the growth process establishes the need for simultaneous control of crystal rotation and the crucible and enclosure wall temperature, along with the pull velocity for growth of high quality constant diameter YAG crystals.

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Ion Induced Damage and their Annealing in LiTaO3 Single Crystal

MRS Proceedings ◽

10.1557/proc-396-273 ◽

1995 ◽

Vol 396 ◽

Author(s):

Z Zhang ◽

I.A. Rusakova ◽

W.K. Chu

Keyword(s):

Curie Temperature ◽

Single Crystal ◽

Single Crystals ◽

Thermal Annealing ◽

Crystalline Structure ◽

Room Temperature ◽

Complete Recovery ◽

Oxygen Ions ◽

Annealing Temperatures ◽

Crystal Interface

AbstractLiTaO3 single crystals have been implanted with 100 keV oxygen ions at room temperature with doses of 1×1014 /cm2,6xl014/cm2,1.2x1015/cm2, 6xl015/cm2, and 2xl016/cm2. Annealing temperatures ranged from 550 °C to 1075 °C. RBS-channeling and TEM were used for characterization. For partially damaged samples, complete recovery of the crystalline structure was achieved after annealing at 550 °C, which is below the Curie temperature. For totally amorphized samples, thermal annealing induced multidomain growth. These domains extend beyond the original amorphous/crystal interface deep into bulk (1 – 1.5 μm ).

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Effects of Grain Boundary Constraint on the Constitutive Response of Tantalum Bicrystals

MRS Proceedings ◽

10.1557/proc-779-w6.4 ◽

2003 ◽

Vol 779 ◽

Cited By ~ 1

Author(s):

A. Ziegler ◽

G. H. Campbell ◽

M. Kumar ◽

J. S. Stölken

Keyword(s):

Grain Boundary ◽

Single Crystals ◽

Boundary Region ◽

Twist Boundary ◽

Compression Tests ◽

Large Area ◽

Crystal Rotation ◽

Boundary Constraint ◽

Free Region ◽

Constitutive Response

AbstractThe role of grain boundary constraint in strain localization, slip system activation, slip transmission, and the concomitant constitutive response was examined performing a series of uniaxial compression tests on tantalum bicrystals. Tantalum single crystals were diffusion bonded to form a (011) twist boundary and compressed along the [011] direction. The resulting threedimensional deformation was analyzed via volume reconstruction. With this technique, both the effective states of stress and strain over the cross-sectional area could be measured as a function of distance from the twist boundary, revealing a highly constrained grain boundary region. Post-test metallurgical characterization was performed using Electron Back-Scattered-Diffraction (EBSD) maps. The results, a spatial distribution of slip patterning and mapping of crystal rotation around the twist-boundary, were analyzed and compared to the known behavior of the individual single crystals. A rather large area near the grain boundary revealed no crystal rotation. Instead, patterns of alternating crystal rotation similar to single crystal experiments were found to be some distance away (~1mm) from the immediate grain boundary region, indicating the large length scale of the rotation free region.

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