Abstract

Conductive high transmission coatings for the UV and near IR are described. The predicted and observed dependence of coating transmission on metal layer sheet resistance and refractive index of the dielectric layer are compared. Computer-generated transmission/layer thickness maps are used for multilayer design sensitivity analysis. Coatings made from Ta₂O₅/Ag/Ta₂O₅ with the design 0.62λ/(150-220-Å) Ag/0.12λ had the best UV transmission, near 80% on glass between 330- and 450-nm wavelengths. Metal layer sheet resistance ranged from 2 to 10 Ω/sq. Coatings with Nb₂O₅ layers had similar transmissions, and worked best above the 380-nm wavelength. Near-IR coatings were made from Si/Ag/Si combinations. Transmissions near 80% on glass at 1400 nm were achieved by a 0.19λ/200-Å Ag/0.19λ design. The high refractive index (~3.4) of the Si layers made high transmissions possible. All coatings were fabricated by dc magnetron reactive sputtering using metal targets (Ta, Nb, Si, Ag) and either Ar or Ar + O₂ gases. Even though substrate temperatures were <40°C, care was taken to prevent Ag oxidation or diffusion into the dielectric. The coatings are useful for any applications requiring high UV and near-IR transmission, high conductivity, and high-IR reflectance.

© 1986 Optical Society of America