crystal sapphire has a unique combination of physical,
chemical and optical properties allowing it to withstand
high temperatures, high pressure, thermal shock, and water
or sand erosion. It is chemically inert, with a low friction
coefficient, and excellent electrical, optical, and dielectric
characteristics. In addition, its radiation resistance
makes it an excellent material for use in optical windows
for space applications
Sapphire has a hexagonal/rhombohedral
structure and a number of properties are dependant on
the orientation of the crystal. For epitaxial growth
of films, different orientations will offer a range
of lattice constants to match the epi material.
C-plane sapphire substrates are used
to grow III-V and II-VI compounds such as GaN for blue
LED and laser diodes. In addition, it is useful for
infrared detector applications.
A-plane sapphire substrates provide a uniform dielectric
constant and high insulation for hybrid microelectronic
applications. High Tc superconductors can be grown with
a-plane Sapphire substrates.
R-plane sapphire substrates are used
for the hetero-epitaxial deposition of silicon for microelectronic
IC applications. Sapphire is an excellent choice for
hybrid substrates such as microwave IC's because of
its high dielectric constant. In addition, when filmed
with an epitaxial silicon process, high speed IC and
pressure transducers can be created. Growing thallium,
other superconducting components, high impedance resistors,
and GaAs are other applications.
*Chemical resistance - high inert and resistance of
sapphire makes it's character hard to be changed in
most process environments including hydrofluoric acid
and the fluorine plasma applications generally in semiconductor
wafer processing. Quartz and polycrystalline alumina
and other ceramics are damaged and corroded in similar
environments.sapphire windows and optics remain free
will not contaminate during processing.
properties - A high, stable dielectric constant with
the electrical insulation required for electronic substrates,
RF and microwave transmitting windows and tubes.
ensures consistent electrical properties.
properties -A high stiffness (modulus),high strength,
provides excellent wear resistance for application environments.strong
stiffness enable bear high pressures and keep long life
transmission -Ranges from below 0.2 microns, to over
4 microns, combined with the excellent chemical durability,
wear resistance, stiffness, and high temperature performance
enables sapphire widely used for windows,sensor optics,
high performance vacuum systems and other optical applications.
used in window and optic applications where the process
environment would destroy conventional glass or quartz
optics many applications in wavelength regions beyond
quartz transmission range no UV solarization.
treatments - sapphire can be polished to very tight
flatness and smoothness for substrate applications and
precision mechanical components.
properties - with a melting point over 2000 oC, and
high thermal conductivity - sapphire is often used in
many harsh process environments for a combination of
its thermal, chemical, mechanical, and optical properties.
properties - with high hardness and transparency, sapphire
is used for scratch proofing in high wear applications
and for precision mechanical components.