Application of silver-dispersed AlN thin film to solar control glass

Solar reflective multilayered films which mainly reflect near-infrared rays in solar radiation but transmit radio waves were prepared by dispersing fine silver particles in an AlN layer of the film. The silver particle-dispersed AlN film was fabricated by heating the film consisting of three layers of AlN, Ag, and AlN. A theoretical equation regarding the reflection–wavelength relationship was derived based on the assumption that the power reflection coefficient of dielectric film, in which metal particles are randomly dispersed, is expressed by the reflection from many domains of different sizes, each domain consisting of periodic conductive square segments. Comparing the theoretical values of reflection for silver-dispersed AlN thin film with the observed ones allows us to estimate the mean size and thickness of silver particle to be 130 and 18 nm, respectively. This suggests that the frequency selective screen which reflects only near-infrared rays can be designed by controlling the size of silver particles.