Visible and near infrared light absorbance of Ag thin films deposited on ZnO under layers by magnetron sputtering

Abstract

The correlation among the electrical, optical and structural properties of Ag thin films was investigated. Low-emissivity (low-e) coatings consisting of glass/ZnO/Ag were deposited by magnetron sputtering. The ZnO thin films were deposited under various oxygen gas pressures to vary the property of Ag thin films deposited on them. When the ZnO thin films were deposited in low oxygen gas pressure, the Ag thin films deposited on the ZnO thin films exhibited low resistivity and smooth surface. Besides, it was found that the low-emissivity coatings with low visible and near infrared light absorbance were obtained using the low-resistive and smooth Ag thin films. It was concluded from the results that the light absorbance became low with decreasing the resistivity of Ag thin films in accordance with Drude's theory in the case where the Ag thin films exhibited sufficiently smooth surface. Furthermore, it can be considered that the surface plasmon polariton of Ag thin films had an influence on the optical property when their surface became rough. The optical absorbance of the low-e coatings should be determined as the result of the competition between two factors: resistivity and surface roughness of Ag thin films.