vii
TABLE OF CONTENTS
CHAPTER
TITLE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xi
LIST OF FIGURES
xii
LIST OF SYMBOLS
xvi
LIST OF ABBREVIATIONS
LIST OF APPENDICES
1
PAGE
xviii
xix
INTRODUCTION
1.1
Problem Background
1
1.2
Problem Statement
4
1.3
Objectives of Research
5
1.4
Scope of Research
6
1.5
Significance of Research
6
1.6
Thesis Plan
7
1.7
Research Flow Chart
8
viii
2
LITERATURE REVIEW
2.1
Introduction
9
2.2
Czochralski Crystal Growth
9
2.2.1
10
Basic Principles of Czochralski Crystal
Growth
2.2.2
Crystal / Crucible Rotation
15
2.2.3
Pulling Rate
17
2.2.4
Growth Rate
18
2.2.5
Growth Direction
21
2.3
Diameter Control
23
2.4
Automatic Diameter Control – Crystal Growth
25
System (ADC-CGS)
2.4.1
2.5
26
2.4.1.1
Power Control
27
2.4.1.2
Diameter Control
28
2.4.1.3
Diameter Calculation
29
2.4.1.4
Power Adjustments
31
Sapphire
2.5.1
3
ADC Program Control Process
33
Titanium-doped Sapphire (Ti:Sapphire)
37
2.6
Density
38
2.7
Porosity
39
2.8
Hardness
41
2.9
Young’s Modulus
43
2.10
X-Ray Diffraction
44
2.11
Energy Dispersive X-Ray Analysis
46
RESEARCH METHODOLOGY
3.1
Introduction
49
3.2
Sample Preparation
49
3.2.1
Raw Material Preparation
50
3.2.2
Seed Crystal Preparation
50
3.2.3
Hot Zone Set Up
51
3.2.4
Growth Process
54
ix
3.2.5
3.3
4
Slicing and Polishing
60
Sample Characterization
60
3.3.1
Density
60
3.3.2
Porosity
61
3.3.3
Vickers Hardness Test
62
3.3.4
Young’s Modulus
63
3.3.5
X-Ray Diffraction (XRD) Analysis
64
3.3.6
Energy Dispersive X-Ray (EDAX) Analysis
65
RESULTS AND DISCUSSIONS
4.1
Introduction
66
4.2
Growth of Ti:Sapphire Crystals
67
4.3
Growth Parameter Analysis
70
4.3.1
70
Correlation of Control Power and
Temperature to the Growth Process
4.3.2
Effect of Control Power on the Crystal
75
Diameter
4.3.3
Effect of Growth Rate on the Crystal
85
Diameter
4.4
X-Ray Diffraction (XRD) Analysis
88
4.5
Chemical Composition Assessment by Energy
92
Dispersive X-Ray (EDAX) Analysis
4.6
Effect of Rotation Speed and Pulling Rate on
93
Density
4.7
Effect of Rotation Speed and Pulling Rate on
97
Porosity
4.8
Effect of Rotation Speed and Pulling rate on
99
Hardness
4.9
Effect of Rotation Speed and Pulling Rate on
Young’s Modulus
103
x
5
CONCLUSIONS AND SUGGESTIONS
5.1
Introduction
108
5.2
Conclusions
108
5.3
Suggestions
111
REFERENCES
112
APPENDICES
123
xi
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Main Characteristic of Sapphire
35
3.1
Aspects of growth conditions used in the experiment
57
3.2
Setting parameters for Ti:Sapphire crystal growth
58
3.3
Summary of growth parameters used to grow
Ti:Sapphire single crystal
59
4.1
Chemical composition for selected Ti:Sapphire crystals
92
4.2
Density value for Group A crystals
93
4.3
Density value for Group B crystals
95
4.4
Porosity value for Group A crystals
97
4.5
Porosity value for Group B crystals
98
4.6
Vickers hardness number obtained from Group A crystals
100
4.7
Vickers hardness number obtained from Group B crystals
101
4.8
Young’s Modulus value for Group A crystals
104
4.9
Young’s Modulus value for Group B crystals
105
xii
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Research flow chart
8
2.1
Basic elements of a Czochralski crystal growth
11
2.2
The phases of Czochralski technique crystal growth
14
2.3
Surface and bulk fluid flows on simulation experiment in a
Czochralski system
16
2.4
Parameters for growth rate determination
18
2.5
LiTaO3 crystals grown along different growth directions
22
2.6
Crystal Weighing Technique
24
2.7
Diameter control by optical technique
25
2.8
First 12 control parameters of ADC program
26
2.9
The principal control loop in ADC Program
27
2.10
The control loop regarding diameter control
28
2.11
Reading of weight versus time are gathered at intervals
defined by Weight Reading Interval parameter – C(24).
and Diameter Update Interval parameter – C(25)
29
2.12
Hypothetical trace of the measured diameter as function of
time for Point A, Point B and Point C
33
2.13
Structure and crystallographic planes of Sapphire
34
xiii
2.14
Synthetically grown titanium-doped sapphire single
crystals
37
2.15
Schematic diagram of diamond pyramid indenter and the
diagonals of the indentation on the specimen surface
42
2.16
X-ray diffraction diagram
46
2.17
Example of EDAX spectrum
47
2.18
The emission of X-ray photon energies
48
3.1
Ti:Al2O3 polycrystalline bulk pellet with nominal dopant of
0.20 wt. % Ti, with reference to a coin
50
3.2
Design layout for hot zone insulation
52
3.3
ZrO2 ceramic discs for the hot zone
53
3.4
Al2O3 tubes used placed on top of the ZrO2 insulators
53
3.5
Complete setup for the hot zone insulation
54
3.6
Automatic Diameter Control – Crystal Growth System
55
3.7
Seed crystal and seed holder configuration
56
3.8
AND Model GR200 densitometer
61
3.9
Two diagonals of the indentation left on the surface of the
material
62
3.10
CV Instruments Vickers Hardness Tester Model 450AAT
63
3.11
INSTRON Universal Testing Machine Model 3882
64
3.12
Siemens Diffractometer D5000
65
4.1
Group A crystals with a fixed pull rate of 1.50 mm h-1 and
varying crystal rotation speed
68
4.2
Group B crystals grown with a fixed seed rotation speed of
15 rpm and varying pull rate
69
xiv
4.3
Variation of control power and temperature against growth
elapsed time for Sample A1 at pulling rate 1.50 mm h-1 and
rotation speed 8 rpm
72
4.4
Variation of control power and temperature against growth
elapsed time for Sample B1 at pulling rate 0.75 mm h-1 and
rotation speed 15 rpm
72
4.5
Variation of control power and temperature against growth
elapsed time for Sample B2 at pulling rate 1.00 mm h-1 and
rotation speed 15 rpm
73
4.6
Variation of control power and temperature against growth
elapsed time for Sample B5 at pulling rate 1.75 mm h-1 and
rotation speed 15 rpm
73
4.7
Variation of control power and measured diameter against
growth elapsed time for Sample A2 at pulling rate 1.50
mm h-1 and rotation speed 12 rpm
77
4.8
Variation of control power and measured diameter against
growth elapsed time for Sample A3 at pulling rate 1.50
mm h-1 and rotation speed 16 rpm
79
4.9
Variation of control power and measured diameter against
growth elapsed time for Sample A5 at pulling rate 1.50
mm h-1 and rotation speed 24 rpm
81
4.10
Variation of control power and measured diameter against
growth elapsed time for Sample B5 at pulling rate 1.75
mm h-1 and rotation speed 15 rpm
83
4.11
Variation of measured diameter and growth rate against
growth elapsed time for Sample A2 at pulling rate of 1.50
mm h-1 and rotation speed 12 rpm
85
4.12
Variation of measured diameter and growth rate against
growth elapsed time for Sample A4 at pulling rate of 1.50
mm h-1 and rotation speed 20 rpm
86
4.13
Variation of measured diameter and growth rate against
growth elapsed time for Sample B1 at pulling rate of 0.75
mm h-1 and rotation speed 15 rpm
86
xv
4.14
Variation of measured diameter and growth rate against
growth elapsed time for Sample B5 at pulling rate of 1.75
mm h-1 and rotation speed 15 rpm
87
4.15
Powder X-Ray pattern of Ti:Sapphire crystal for Sample A1
89
4.16
Powder X-Ray pattern of Ti:Sapphire crystal for Sample A3
89
4.17
Powder X-Ray pattern of Ti:Sapphire crystal for Sample A5
90
4.18
Powder X-Ray pattern of Ti:Sapphire crystal for Sample B1
90
4.19
Powder X-Ray pattern of Ti:Sapphire crystal for Sample B3
91
4.20
Powder X-Ray pattern of Ti:Sapphire crystal for Sample B5
91
4.21
The graph of density against rotation speed implemented on
Group A growth runs
94
4.22
The graph of density against pulling rate implemented on
Group B growth runs
95
4.23
The graph of porosity against rotation speed for Group A
crystals
97
4.24
The graph of porosity against pulling rate for Group B
crystals
99
4.25
Graph of Vickers hardness number against rotation speed for
Group A crystals
100
4.26
Graph of Vickers hardness number against pulling rate for
Group B crystals
102
4.27
Graph of Young’s Modulus against rotation speed for Group
A crystals
104
4.28
Graph of Young’s Modulus against pulling rate for Group B
crystals
106
xvi
LIST OF SYMBOLS
A
-
surface area of residual deformation
A0
-
original cross-sectional area
Ac
-
surface area of crystal interface
d
-
mean diagonal
D
-
ratio of crystal radius to crucible radius
dcryst.
-
diameter of the crystal
dD/dt
-
first derivative of the diameter
dhkl
-
interplanar spacing of the (hkl) spacing
dW/dt
-
first derivative of the crystal
E
-
Young’s Modulus
F
-
peak load
FC
-
force exerted on the specimen under compression
Gc
-
crystal growth rate
Gl
-
amount of liquid crystallized per unit time
H
-
hardness
hc
-
height of crystal grown per unit time or linear growth rate
L
-
height of liquid crystallized per unit time
L0
-
original length of the specimen
Lm
-
liquid level drop
m
-
mass
n
-
integer or order of reflection
P(t)
-
control power at time
Pr
-
sum of the pull rate
rc
-
radius of the crystal
Rcr
-
radius of the crucible
xvii
t
-
time
v
-
volume
Vb
-
bulk volume
Vop
-
open pore volume
W1
-
weight of sample in air
W2
-
weight of sample in liquid
WD
-
weight of the dry sample
WS
-
weight of saturated sample
WSS
-
weight of the saturated sample submerged in liquid
ΔL
-
length displaced over original length
ε
-
strain
θ
-
diffraction angle
κ
-
ratio of average liquid density to solid density of the crystal
λ
-
wavelength of the beam
ρ
-
density
ρair
-
density of air
ρL
-
liquid density
ρliq
-
density of immersion liquid
ρS
-
solid density of the crystal
σ
-
stress
xviii
LIST OF ABBREVIATIONS
ADC
ADC-CGS
CP
Cz
DG
EDAX
err
HV
ICSD
ID
IG
LED
OD
PDF
PG
PI
PID
RF
SEM
T
Ti:Sapphire
WDS
wt.
XRD
-
Automatic Diameter Control
Automatic Diameter Control-Crystal Growth System
control power
Czochralski
derivative gain
Energy Dispersive X-ray
error
Vickers hardness number
Inorganic Crystal Diffraction Database
inside diameter
integral gain
light emitting diode
outside diameter
powder diffraction file
proportional gain
proportional-integral
proportional-integral-derivative
radio frequency
scanning electron microscopy
thickness
titanium-doped sapphire
wavelength dispersive X-ray spectroscopy
weight
X-ray Diffraction
xix
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
ICSD standard powder X-ray diffraction database of
Al2O3 (synthetic corundum)
123
B
ICSD standard powder X-ray diffraction database of
Al2TiO5
124
C
Chemical composition Assessment by Energy
Dispersive X-ray (EDAX) analysis
125
D
Calculation of density
128
E
Porosity calculation
129
F
Vickers hardness number calculation
130
G
Young’s Modulus determination
132
H
EKSPLA titanium-doped sapphire laser crystal
brochure
134
I
Related publication
135