Dynamics of Thermal Field and Powder Sublimation in an Inductively Heated AlN Bulk Crystal Growth Process

2004 ◽  
Author(s):  
Bei Wu ◽  
Hui Zhang
Keyword(s):  
Crystal Growth ◽  
Maxwell Equations ◽  
Thermal Field ◽  
Energy Equation ◽  
Dynamic Responses ◽  
Transient Temperature ◽  
Bulk Crystal Growth ◽  
Transient Temperature Distribution ◽  
Growth System ◽  
Sublimation Growth

In this paper, an integrated model considering induction heating, transient heat transfer and crystal growth has been developed to study dynamic response of temperature and powder sublimation in an aluminum nitride (AlN) growth system. The electromagnetic field and induction heat generation are calculated by the Maxwell equations. Transient temperature distribution in the growth chamber is simulated by energy equation accounting for conduction/radiation within and between various components. In order to provide proper temperature control during sublimation growth, dynamic responses of temperature and temperature difference of the bottom and top external surfaces of the growth crucible to power variation and coil position movement are simulated. Finally the crystal and powder shapes as a function of time are predicted and compared with dynamic experimental observation.

Inverse-Computation Design of a SiC Bulk Crystal Growth System

2000 ◽  
Vol 640 ◽  
Author(s):  
Alexey V. Kulik ◽  
Svetlana E. Demina ◽  
Sergey K. Kochuguev ◽  
Dmitry Kh. Ofengeim ◽  
Sergey Yu. Karpov ◽  
...  
Keyword(s):  
Thermal Field ◽  
Crystal Shape ◽  
Temperature Uniformity ◽  
Powder Charge ◽  
Bulk Crystal Growth ◽  
Term Operation ◽  
Growth System ◽  
Selective Sensitivity ◽  
Sublimation Growth

ABSTRACTInverse modeling was applied to the optimization of a crucible design for SiC sublimation growth. We found a crucible shape providing the optimal temperature distribution in terms of the powder source stability during long-term operation and of the convex crystal shape. Considerable improvement of temperature uniformity throughout the powder charge was achieved. The results obtained show selective sensitivity of the thermal field inside the crucible to modification of the crucible design. The inverse problem approach is easy-to-adapt to various optimization criteria and seems to be especially effective in the case of multi-factor optimization.

Defect Formation During Sublimation Bulk Crystal Growth of Silicon Carbide

1998 ◽  
Vol 510 ◽  
Author(s):  
Noboru Ohtani ◽  
Jun Takahashi ◽  
Masakazu Katsuno ◽  
Hirokatsu Yashiro ◽  
Masatoshi Kanaya
Keyword(s):  
Silicon Carbide ◽  
Crystal Growth ◽  
Defect Formation ◽  
Stacking Faults ◽  
Growth Direction ◽  
Bulk Crystal ◽  
Structural Defects ◽  
Bulk Crystals ◽  
Bulk Crystal Growth ◽  
Sublimation Growth

AbstractThe defect formation during sublimation bulk crystal growth of silicon carbide (SiC) is discussed. SiC bulk crystals are produced by seeded sublimation growth (modified-Lely method), where SiC source powder sublimes and is recrystallized on a slightly cooled seed crystal at uncommonly high temperatures (≥2000°C). The crystals contain structural defects such as micropipes (hollow core dislocations), subgrain boundaries, stacking faults and glide dislocations in the basal plane. The type and density of the defects largely depend on the crystal growth direction, and many aspects are different between the growth parallel and perpendicular to the <0001> c-axis. Micropipes are characteristic defects to the c-axis growth, while a large number of stacking faults are introduced during growth perpendicular to the c-axis. We discuss the cause and mechanism of the defect formation

Simulation of Gravity Effects on Bulk Crystal Growth with Effects on Undercooling

2010 ◽  
Vol 154-155 ◽  
pp. 1538-1543 ◽  
Author(s):  
Ming Fang Lu ◽  
Shu Hao Chuang ◽  
Hsing Juin Lee
Keyword(s):  
Crystal Growth ◽  
Gravitational Acceleration ◽  
Two Dimensional ◽  
Bulk Crystal Growth ◽  
Gravity Effects ◽  
Interface Location ◽  
Growth System ◽  
Vertical Bridgman ◽  
Kinetic Undercooling ◽  
Crystal Interface

The effects of gravity and kinetic undercooling upon the melt/crystal interface in a vertical Bridgman-Stockbarger crystal growth system by numerical simulation. Thermal transport, melt convection and kinetic undercooling are simulated by two-dimensional transient calculations. Time evolution of the centerline interface location difference is tracked. This study then compares and discusses the results among the different gravitational acceleration. We also investigate the effects of the undercooling on the interface.

Modeling Analysis of Free-Spreading Sublimation Growth of SiC Crystals

2002 ◽  
Vol 742 ◽  
Author(s):  
M. V. Bogdanov ◽  
S. E. Demina ◽  
S. Yu Karpov ◽  
A. V. Kulik ◽  
D. Kh Ofengeim ◽  
...  
Keyword(s):  
Thermal Field ◽  
Crystallization Front ◽  
Thermoelastic Stress ◽  
Bulk Crystals ◽  
Advanced Technique ◽  
Powder Charge ◽  
Modeling Analysis ◽  
Growth System ◽  
Sublimation Growth ◽  
Front Dynamics

ABSTRACTRecently, an advanced technique for growing free-spreading SiC bulk crystals by sublimation has been demonstrated. This method was used to grow 6H- and 4H-SiC boules free of polycrystalline deposits on the crystal periphery, up to 35 mm in diameter with the micropipe density less than 20 cm-2 and the dislocation density about 102-103 cm-2. In this paper, we report on the numerical modeling of free-spreading crystal growth. We consider the global heat transfer in an inductively heated growth system, species transport in the growth cell and in the powder charge, and thermoelastic stress, focusing on the crystallization front dynamics, poly-SiC deposition, and powder source evolution. Special attention was given to the validation of the simulations. The computed thermal field and evolution of the powder and crystal shape were found to agree qualitatively with observations.

Modeling of PVT Growth of Bulk SiC Crystals: General Trends and 2” to 4” Reactor Scaling

2000 ◽  
Vol 616 ◽  
Author(s):  
M.S. Ramm ◽  
A.V. Kulik ◽  
I.A. Zhmakin ◽  
S.Yu. Karpov ◽  
O.V. Bord ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Numerical Modeling ◽  
Crystal Growth ◽  
Heat And Mass Transfer ◽  
Bulk Crystal ◽  
Deposit Formation ◽  
Bulk Crystal Growth ◽  
Self Consistent ◽  
Growth System

AbstractWe report on study of a growth system upscaling from 2” to 4” using numerical modeling. The model applied involves heat and mass transfer computations combined with a self-consistent analysis of deposit formation on the reactor walls. General trends in SiC bulk crystal growth originated from upscaling are discussed in detail.

A niching genetic algorithm applied to optimize a SiC-bulk crystal growth system

2017 ◽  
Vol 468 ◽  
pp. 914-918 ◽  
Author(s):  
Juan Su ◽  
Xuejiang Chen ◽  
Yuan Li ◽  
Michel Pons ◽  
Elisabeth Blanquet
Keyword(s):  
Genetic Algorithm ◽  
Crystal Growth ◽  
Bulk Crystal ◽  
Bulk Crystal Growth ◽  
Growth System

Design and Optimization of an Aluminum Nitride Sublimation Growth System

2003 ◽  
Author(s):  
Bei Wu ◽  
Ronghui Ma ◽  
Hui Zhang
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Aluminum Nitride ◽  
Elastic Stress ◽  
Transient Temperature ◽  
Design And Optimization ◽  
Transient Temperature Distribution ◽  
Growth System ◽  
Growth Method

In this paper, an integrated model considering induction heating, heat transfer, growth kinetics and thermo-elastic stress has been developed to study temperature distribution in the growth system, crystal shape and stress distribution in the asgrown aluminum nitride (AIN) crystal. The electromagnetic field and induction heat generation are calculated by the Maxwell equations. Transient temperature distribution in the growth chamber is simulated by energy accounting for conduction/radiation within and between various components. To reduce thermal stress and dislocation, a growth method to enlarge the ingot diameter from a smaller seed and maintain low thermal stress in the crystal has been proposed. The thermo-elastic stress fields have been calculated for several designed temperature profiles along the crucible inner wall and stress distribution has been correlated to dislocation density distribution.

Experimental and Theoretical Analysis of Heat and Mass Transport in the System for AlN Bulk Crystal Growth

2002 ◽  
Vol 743 ◽  
Author(s):  
M. V. Bogdanov ◽  
S. Yu. Karpov ◽  
A. V. Kulik ◽  
M. S. Ramm ◽  
Yu. N. Makarov ◽  
...  
Keyword(s):  
North Carolina ◽  
Crystal Growth ◽  
Mass Transport ◽  
State University ◽  
Heat And Mass Transport ◽  
Bulk Crystal Growth ◽  
North Carolina State University ◽  
Model Predictions ◽  
Growth System ◽  
Mass Transport Mechanisms

ABSTRACTBulk AlN crystal growth by Physical Vapor Transport (PVT) is studied both experimentally and numerically. This paper presents the analysis of heat and mass transport mechanisms in closed and partially open crucible geometries. The heat transfer in the growth system used at North Carolina State University (NCSU) is simulated. The computed temperature profiles are used in the analysis of mass transport in the growth cell to gain understanding of the effect of species exchange between the crucible and environment on the AlN growth rate. The model predictions are in reasonable agreement with observations.

TEM and cathodoluminescence of precipitates in II-VI semiconductors

1988 ◽  
Vol 46 ◽  
pp. 488-489
Author(s):  
Joanna L. Batstone
Keyword(s):  
Crystal Growth ◽  
Band Gap ◽  
Local Strain ◽  
Wide Band ◽  
Optoelectronic Device ◽  
Wide Band Gap ◽  
Bulk Crystal Growth ◽  
Transmission Electron ◽  
Device Applications ◽  
Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

CONVECTIVE INSTABILITY IN CRYSTAL GROWTH SYSTEM

2002 ◽  
Vol 12 (12) ◽  
pp. 187-221 ◽  
Author(s):  
Koichi Kakimoto ◽  
Nobuyuki Imaishi
Keyword(s):  
Crystal Growth ◽  
Convective Instability ◽  
Growth System
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