Silicon is used as an optical window primarily
in the 3 to 5 micron band and as a substrate for production of
optical filters. It is frequently used for laser mirrors because
of its high thermal conductivity and low density. Silicon is also
useful as a transmitter in the 20 micron range. Large blocks wi
th polished faces are also employed as targets in neutron physics
experiments.Silicon is grown by Czochralski pulling techniques
(CZ) and contains some oxygen which causes an absorption band
at 9 microns. To avoid this, material can be prepared by a Float-Zone
(FZ) process. Optical silicon is generally lightly doped ( 5 to
40 ohm cm) for best transmission above 10 microns. Silicon has
a further pass band 30 to 100 microns which is effective only
in very high resistivity uncompensated material.
MATERIAL
