Sputter-Deposited Low-Emissivity Coatings on Glass

Low-emissivity (low-E) and solarcontrol coatings increase the energy efficiency of clear float soda-lime-silicate glass for architectural and automotive window applications. At the same time, coated glass largely maintains its neutral color and high visible transmittance. Two major classes of coated products are currently available for the architectural market: The more durable chemicalvapor- deposition (CVD) coatings are deposited on float glass as it is formed. The vacuum deposited low-E coatings, which are the subject of this article, have superior spectral performance and are deposited off-line by the sputter-deposition process. Many elements of this subjecthave been discussed in the literature, covering energy efficiency for windows, specific examples of low-E coating, a J2 6 brief outline of the deposition techniques, and a more detailed account of optical design considerations for low-E thin-film coatings, particularly for single metal-layer systems. This article briefly discusses aspects of these coatings that relate to their design, performance, and preparation. More attention is given to the materials that constitute the different layers of these coatings and to their specific properties and function.