SEDL / STP / STP954-EB / STP23125S

Characterization of Aluminum Nitride/Aluminum Oxide Reactively Sputtered Antireflection Coatings

Koshigoe, LG
Michelson Laboratory,

Johnson, LF
Michelson Laboratory,

Donovan, TM
Michelson Laboratory,

Marrs, CD
Michelson Laboratory,

Pages: 20    Published: Jan 1986

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Abstract

Aluminum nitride/aluminum oxide multilayer protective antireflection coatings are being developed for use on laser windows. These materials have been shown to be relatively stable and scratch resistant, thus demonstrating their applicability for this use. Both two- and three-layer coatings were designed at the wavelength 0.500μm. The design techniques utilized, as well as the resulting transmission spectra, are discussed. Single-layer films have been deposited on fused quartz and calcium fluoride substrates, and a three-layer film has been deposited on a fused quartz substrate. Studies of the resistance of these films to various environmental conditions including laser radiation, fluorine, electron beam irradiation, and humidity are presented. Surface analysis techniques such as scanning Auger microscopy (SAM), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS), and Nomarski microscopy were used to examine coating composition and stoichiometry. Preliminary measurements on the laser resistance of the materials indicate that damage at defects is the predominant failure mode.