Almaz Optics, Inc.
12 Chadsford Ct.  Marlton, NJ 08053, USA
Tel:  856 797-0491, Fax: 856 797-0228
e-mail: mail@almazoptics.com

 

SAPPHIRE, Al2O3

Single crystal sapphire possesses a unique combination of excellent optical, physical and chemical properties. The hardest of the oxide crystals, sapphire retains its high strength at high temperatures, has good thermal properties and excellent transparency. It is chemically resistant to common acids and alkali at temperatures up to 1000 °C as well as to HF below 300 °C. These properties encourage its wide use in hostile environments where optical transmission in the range from the vacuum ultraviolet to the near infrared is required. Sapphire is anisotropic hexagonal crystal. Its properties depend on crystallographic direction (relative to the optical C-axis).
Maximum available size for windows, lenses and blanks made of high purity optical grade single Kyropulos grown Sapphire: 250 mm Dia x 120 mm Thk and 175 mm Square x 120 mm Thk.
Also available Semiconductor Epi polished wafers and substrates for blue LEDs (Nitride based devices).
Sapphire grown by EFG method is available in form of round rods (1-8 mm Dia, up to 500 mm long), rectangular and square rods and ribbons (10-80 mm wide, 1-10 mm thick, 150-500 mm long), tubes, thermocouple sleeves, crucibles  (1.5-50 mm ID, 0.5-4.0 mm wall thickness, up to 600 mm long) and other custom cross-section configurations.

   

 

Main Properties

Chemical Formula Al2O3
Crystal Class Trigonal
Molecular Weight 101.94
Density, g/cm3 (20 °C) 3.98
Reflection Loss, % for two surfaces at 4 µm 12
Dielectric Constant for 103-109 Hz at 298 K
parallel to C-axis
perpendicular to C-axis
11.5
9.3
Dielectric Strength, KV/mm 17
Resistivity at 20°C, Ohm cm > 10 16
Melting Temperature, K 2300
Thermal Conductivity, W/(m K) at 300 K
parallel
perpendicular
35.1
33.0
Thermal Expansion, 1/K at 293 K
parallel
perpendicular
5.6 x 10-6
5.0 x 10-6
Specific Heat, cal/(g K) at 298 K 0.18
Bandgap, eV 9.9
Solubility in water None
Mohs Hardness 9
Knoop Hardness, kg/mm2 1370
Young's Modulus, GPa 335
Shear Modulus, GPa 148
Bulk Modulus, GPa at 273 K 240
Apparent Elastic Limit, MPa 275
Poisson's Ratio 0.25

Transmission (through 2 mm thick sample)

Refractive Index

µm No Ne µm No Ne µm No Ne
0.337 1.80082 1.79206 0.694 1.76341 1.75542 2.703 1.719 1.711
0.351 1.79693 1.78825 0.755 1.76141 1.75346 2.941 1.712 1.704
0.355 1.79598 1.78732 0.78 1.76068 1.75274 3.333 1.701 1.693
0.442 1.78038 1.77206 0.8 1.76013 1.7522 3.704 1.687 1.679
0.458 1.77843 1.77015 0.82 1.75961 1.75168 4 1.674 1.666
0.488 1.7753 1.76711 0.98 1.75607 1.74819 4.348 1.658 1.65
0.515 1.77304 1.76486 1.064 1.75449 1.74663 4.762 1.636 1.628
0.532 1.7717 1.76355 1.32 1.75009 1.74227 5 1.623 1.615
0.59 1.76804 1.75996 1.55 1.74618 1.73838 5.263 1.607 1.599
0.633 1.7659 1.75787 2.01 1.73748 1.72973
0.67 1.76433 1.75632 2.24929 1.73232 1.72432

 


Minimal Recommended Window Thickness

sapphire11.gif (4469 bytes)

 

Strain Gage Applications
Substrate Diameter, mm 50.8 (+/-0.1), 76 (+/-0.5), 100 (+/-0.5)
Substrate Orientation (1012) R (+/-0.5º)
Substrate Thickness, µ 330-430, 450, 460 (+/-25)
Silicon Layer Orientation (100)
Silicon Layer Thickness, µ 0.5-5.0 (+/-8%)
Silicon Conductivity Type (dopant) p (Boron)
Silicon Resistivity, Ohm/sq 10-30 (+/-8%)
Back side finish Ground

CMOS, MEMS Applications
Substrate Diameter, mm 50.8 (+/-0.1), 76 (+/-0.5), 100 (+/-0.5)
Substrate Orientation (1012) R (+/-0.5º)
Substrate Thickness, µ 330-430, 450, 460 (+/-25)
Silicon Layer Orientation (100)
Silicon Layer Thickness, µ 0.1-1.0 (+/-8%)
Silicon Conductivity Type (dopant) n (Phosphorous)
p (Boron)
i (undoped)
Silicon Resistivity, Ohm*cm 0.003-100
Back side finish Ground

Other thickness and laser marking available on request

Semiconductor Substrates

Substrates are available in all orientations including R-axis, C-axis, A-axis and M-axis, in a circular shape from 50.8 to 152 mm diameter.  Thickness available in 0.33 - 1.0 mm range. Primary flats per SEMI Standard are provided on circular substrates, secondary flats and custom surface finish are available on request.

Tolerances Diameter: +/- 0.05 mm
Thickness: +/- 0.05 mm
Orientation: +/-1º
(+/-0.1º on request)
Front Surface Epi polished
Back Side Lapped or polished
Flatness < 2.5 microns per inch
Surface Roughness (Ra) < 0.2 nm

 

Substrates for Nitride Based Devices (Blue LEDs)

Diameter 50.8 +/-0.05, mm  76.2 +/-0.05, mm  101.6 +/-0.05, mm 
Thickness 330, 430 +/-25 µ 380, 430, 480 +/-25 µ 430, 500, 725 +/-25 µ
Orientation C (0001) +/-0.1º C (0001) +/-0.1º C (0001) +/-0.1º
TTV < 10 µ < 10 µ < 20 µ
Bow < 5 µ < 10 µ < 10 µ
Front Surface

Epi polished
Back Side

Lapped or optically polished
Flatness < 5 µ < 7 µ < 8 µ
Roughness (Ra) < 0.2 nm < 0.2 nm < 0.2 nm
Primary Flat Length 16.0 +/-0.8 mm 22.0 +/-0.8 mm 32.5 +/-0.8 mm
Primary Flat Location A or M axis +/- 0.3º A or M axis +/- 0.3º A or M axis +/- 0.5º
Secondary Flat Location 90º counterclockwise to primary flat
Package

Single wafer pack or 25 wafers cassette