Sapphire
Single crystal Sapphire possesses a unique combination
of excellent optical, physical and chemical properties, the most
useful is that it is the hardest of the oxide crystals. Sapphire
maintains its strength even at high temperatures. It has good
thermal properties, excellent electrical and dielectric properties,
and is chemically resistant to common acids and alkali at
temperatures up to 1000? as well as to HF below 300?.
Sapphire is anisotropic hexagonal crystal. Its properties
depend on crystallographic direction (relative to the optical
C-axis). Large sized sapphire crystals up to 4 inches in diameter
are available in OP-Unite. OP-Unite's sapphire crystals are produced
by two method--TGT and Czochraski for the highest optical and
substrate quality.
Main Properties
| Crystal properties |
| Crystal Growth Method |
Czochralski or TGT |
| Maximum Size |
<F100mm |
| Optical properties |
| Transmission Range |
0.15~5.5um |
| Reflection Loss, for two surfaces at 5 ¦Ìm |
14% |
| dn/dt (@633nm), /K |
13x10-6 |
| Refractive Index |
See below |
| Wavelength (um) |
No |
Ne |
Wavelength (um) |
No |
Ne |
| 0.185 |
/ |
/ |
0.800 |
1.76013 |
1.7522 |
| 0.193 |
1.92879 |
1.91743 |
1.064 |
1.75449 |
1.74663 |
| 0.213 |
1.88903 |
1.87839 |
1.320 |
1.75009 |
1.74227 |
| 0.226 |
1.87017 |
1.85991 |
1.550
|
1.74618 |
1.73838 |
| 0.248 |
1.84696 |
1.83719 |
2.010 |
1.73748 |
1.72973 |
| 0.266 |
1.83304 |
1.82358 |
2.703 |
1.71900 |
1.71100 |
0.280
|
1.82437
|
1.81509 |
3.333 |
1.70100 |
1.69300 |
0.308
|
1.81096
|
1.80198 |
3.704 |
1.68700 |
1.67900 |
0.355
|
1.79598
|
1.78732
|
4.000 |
1.67400 |
1.66600 |
| 0.488 |
1.7753 |
1.76711
|
4.348 |
1.65800 |
1.65000 |
| 0.532 |
1.7717 |
1.76355 |
4.762 |
1.63600 |
1.62800 |
| 0.633 |
1.7659 |
1.75787 |
5.000 |
1.62300 |
1.61500 |
| 0.780 |
1.76068
|
1.75274 |
5.263 |
1.60700 |
1.59900 |
| Transmission Curve |
See below |
|
| Crystallographic properties |
| Syngony |
Hexagonal System |
| Crystal Form |
Poly or Single Crystal |
| Lattice Constant, Å |
7a=4.785, c=12.991 |
| Cleavability |
<1011>, <1012>, imperfect |
| Physical properties |
| Density, g/cm3 at 20 ¡ãC |
3.98 |
| Hardness, Mohs |
9 |
Dielectric Constant 102-108 Hz at 298 K
Parallel to c-axis (//)
Perpendicular to c-axis (£) |
10.55
8.6 |
| Melting point, ¡ãC |
2042 |
Thermal Conductivity, W/m¡¤K at at 300 K
Parallel to c-axis (//)
Perpendicular to c-axis (£) |
35.1
33.0 |
Thermal Expansion, 1/K at 298 K
Parallel to c-axis (//)
Perpendicular to c-axis (£) |
5.6 ¡Á 10-6
5.0 ¡Á 10-6
|
| Specific Heat Capacity, W¡Ás/g/k |
0.418 |
| Bandgap, eV |
9.9 |
| Knoop Hardness, kg/mm2 |
1370 |
| Young's Modulus, Gpa |
335 |
| Shear Modulus, GPan |
148 |
| Bulk Modulus, Gpa at 273 K |
240 |
| Poisson's Ratio |
0.25 |
| Elastic Coefficient |
C11=496, C12=164, C13=115, C33=498, C44=148 |
| Apparent Elastic Limit |
275 MPa (13000psi) |
| Chemical properties |
| Solubility in water at 20 ¡ãC,
g/100cm3 |
98¡Á10-6 |
| Solubility in acids |
Soluble |
| Molecular Weight |
101.94 |
M ain
Applications
These properties encourage the use of Sapphire in
aggressive environments where reliability, optical transmission or
strength is required. It is have the following wide applications in
the range from the vacuum ultraviolet to the near infrared:
Optical applications:
 Illumination windows
Sapphire light guides
LCD projector windows
Optical components
such as lenses, prisms, other
laser and infrared optics
Medical applications:
Surgical tips
Endoscope lenses
Analytical applications:
Used
in very high-pressure applications in replacement of glass or quartz
tubes in NMR
Sapphire replaces quartz to improve durability and
reduce contamination in mass spectroscopy
Aerospace
applications:
Windows for sensors
Infrared Countermeasure lamps
Electronic
applications: Sapphire substrate with different orientation has
different applications:
1 (0001) Basal Plane Sapphire Substrate:
Epitaxial Gallium Nitride chip for blue LED
IR detector
2 (-1 1 0 2) R-Plane Sapphire
Substrate:
GaAs wafer carriers
Microwave IC
SOS (Silicon on Sapphire)- High Speed IC
Pressure Transducer
3 (1 -1 2 0) A Plane Sapphire
Substrate:
The growth of high Te superconductors
General
Specifications
| Optical Sapphire Windows |
| Chemical properties |
| Parameters |
Commercial grade |
Precision grade |
| Orientation |
C-axis¡À1¡ã, C-axis¡À0.5¡ã, or any orientation as
customers' request |
| Diameter Tolerance |
+0/-0.10mm |
| Thickness Tolerance |
¡À0.10mm |
| Clear Aperture |
>Central 90% of diameter |
| Surface Quality |
60-40 S/D |
40-20 S/D |
| Parallelism |
3~5 arc min |
1 arc min |
| Surface Flatness |
1¦Ë per 25mm |
¦Ë/4 |
| Chamfer |
0.15~0.35mm¡Á45¡ã face width ¡Á 45¡ã¡À15¡ã |
| Coating |
Coatings are available upon request |
| Epi-ready Sapphire Substrates |
| Parameters |
Value |
| Diameter |
50.8¡À0.05mm |
76.2¡À0.05mm |
| Thickness |
330-430¡À50¦Ìm |
380-480¡À50¦Ìm |
| Orientation |
C (0001) ¡À0.2¡ã
A (1120) ¡À0.2¡ã
R (1102) ¡À0.2¡ã |
C (0001) ¡À0.2¡ã
A (1120) ¡À0.2¡ã
R (1102) ¡À0.2¡ã |
| TTV and Bow |
<20¦Ìm |
<25¦Ìm |
| Front Surface |
Epi polished |
Epi polished |
| Back Side |
Lapped or polished |
Lapped or polished |
| Flatness |
<5¦Ìm |
<5¦Ìm |
| Roughness (Ra) |
<0.5¦Ìm |
<0.8¦Ìm |
|
