Thorium-free coating for germanium IR window
AssigneeTexas Instruments Incorporated
InventorsFrank C. Sulzbach, Valeria J. Epling
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Abstract
Durable thorium fluoride, low reflectance, high transmittance coatings for germanium (zinc sulfide, zinc selenide, gallium arsenide) exterior window surfaces are replaced using magnesium fluoride, a material previously not considered applicable to the 8 to 12 .mu.m wavelength range. This is enabled by the use of argon ion bombardment of the growing film. This method reduces the intrinsic stress of deposited films and permits growth of magnesium fluoride films of sufficient thickness to be used on the exterior surface of IR windows.
Claims10
A method of forming a magnesium fluoride coating comprising the steps of:
- (a) disposing a substrate in a chamber;
- (b) ion beam cleaning the surface of said substrate at ion energies of from about 100 eV to about 2000 eV;
- and
- (c) ion aided depositing a layer of magnesium fluoride on said cleaned substrate while bombarding said substrate with inert gas ions having an energy level of from about 1 eV to about 200 eV,
Dependencies are inferred from the claim text.