Numerical Analysis of Liquid Menisci in the EFG Technique (original) (raw)
Related papers
Analysis of the features of meniscus profile curves during growth of base-faceted sapphire ribbons
Bulletin of the Russian Academy of Sciences: Physics, 2009
The dependence of the step parameters on the surface of base faceted sapphire ribbons on the angle of deviation of crystallographic orientation has been measured. A model of step formation on the lateral ribbon surface is proposed. Hysteretic character of the dependence of the lateral ribbon surface inclination on the meniscus angle at the triple point is shown. The shapes of the lateral surfaces are calculated and the range of variation in the meniscus angle is determined.
EFG growth of sapphire tubes upto 85mm in diameter
Journal of Crystal Growth, 1998
Conditions for large tubular sapphire crystal growth have been examined. Single crystalline tubes with outer diameters of upto 85 mm were grown successfully by the EFG technique using a simple one-heater growth assembly. The dependence of structural perfection on growth conditions and die-top design have been investigated. The process for seed enlargement upto the full-circular cross-section was found to be of primary importance for high-quality growth, and a suitable algorithm has been suggested.
Numerical Simulation of the Flow Field and Solute Segregation in Edge-Defined Film-Fed Growth
Crystal Research and Technology, 2001
The purpose of this study is to clarify the effect of hydrodynamics and mass transport on the bubble generation in sapphire shaped crystals. The basic idea is that nucleation of bubbles can be anticipated in places were the gas chemical composition is maximum. Finite elements numerical simulation (FIDAP TM software) is used in order to solve the momentum, mass and chemical species conservation equations in the liquid enclosed in the capillary channel and in the liquid meniscus. A parametric study is performed and the effect of the die geometry and of the physical parameters are clarified. It is shown that the main effect is related to the rejection of the gas at the solid-liquid interface and that forced and thermo-capillary convection can explain the experimental observation of the concentration of microbubbles very close to the outer crystal surface in certain cases.
Journal of Crystal Growth, 2006
The quality of crystals being grown depends to a considerable extent on homogeneity, i.e., on the distribution of both special added and detrimental impurities. Variations of concentration of such impurities along the crystal length and cross-section are determined by processes that takes place in the melt near the crystallization front (interface). These variations of concentration lead to non-uniform spatial, electrical and optical properties in wafers obtained from the crystal. In this paper, the influence of the pulling rate v and of the radius of the capillary channel R cap on the fluid flow and on the aluminum (Al) impurity distribution in a thin silicon (Si) rod, grown from the melt by edge-defined film-fed growth (EFG) method with central capillary channel shaper (CCC), has been studied using numerical simulation. The commercial FEMLAB 3.1 software has been used in order to solve the incompressible Navier-Stokes and conservative convection-diffusion equations in a strictly zero gravity environment, assuming that the flow and the impurity distribution are axisymmetric. The computations were made in the stationary and nonstationary cases, respectively, for a rod of radius R ¼ 1.5 Â 10 À3 m grown with a pulling rate v in the range [10 À7 ; 10 À5 ] m/s, using a meniscus height h ¼ 0.5 Â 10 À3 m. An EFG growth system with a die radius R 0 ¼ 2 Â 10 À3 m was considered for three values of the radius of the capillary channel R cap ¼ 0.5; 1; 1.5 Â 10 À3 m and it was assumed that the melt level in the crucible is constant (continuous melt replenishment).
A review of developments in shaped crystal growth of sapphire by the Stepanov and related techniques
Progress in Crystal Growth and Characterization of Materials, 2002
Contents 1. Introduction 2. Variable Shaping Technique (VST) 3. Noncapillary Shaping (NCS) 3. I. Description of the technique 3.2 The growth of high quality shaped sapphire crystals with large cross-section. 3.2.1 The growth of crystals with a prc-determined cross-sectional shape 3.2.2 The growth of crystals with a variable cross-section 3.2.2.1 Growth near-net shaped dome crystals by the NCS technique 4. Growth from an Element of Shape (GES) 4.1 Control of gas bubbles 4.2 Growth near-net shaped dome crystals 4.3 Critical strain rate criterion for crack-free dome growth 5. Modulation-doped shaped crystal growth 5.1 Periodical doped structures 5.1.1 Obtaining periodic structures by the EFG technique 5.1.2 Obtaining layered crystals by the GES technique 5.2 Core-doped Fibers 5.2.1 Automatization as the base of high-quality core-doped fiber growth
SOLUTE DISTRIBUTION IN SHAPED SAPPHIRE CRYSTALS OBTAINED BY EFG METHOD
2000
One of the specific defects that affect the optical properties of shaped sapphire crystals obtained by Edge-defined Film-fed Growth (EFG) method is the so-called "voids", the trapped gas bubbles. The origin and the distribution of these trapped voids are not yet clarified. In order to study the bubbles and solute distribution sapphire rods and ribbons were obtained by EFG method.
Mechanical Characteristics of Sapphire Ribbons Grown Simultaneously by EFG Method
Crystal Research and Technology, 2018
Mechanical properties of ten sapphire ribbons are studied. These ribbons are grown simultaneously with prismatic orientation ({1120} plane and 1100 direction) with the dimensions 2 × 85 × 400 mm. Strength and plastic characteristics of the crystals are determined on the as-grown and mechanically treated surfaces. Peculiarities of the morphology and distribution of pores in thin subsurface layer are considered.