Deposition of low-emissivity filter by RF magnetron sputtering

초록

A low-emissivity coating of [air|dielectric|metal|dielectric|glass] can be employed to shield the hazard electromagnetic wave and cut off the near infrared(NIR) spectrum in the display appliances. In this study we have repeated a basic [dielectric|metal|dielectric] design to enhance the conductivity and NIR cut-off and investigated the optical and electrical properties of low-emissivity filter prepared by RF magnetron sputtering. The basic design was [TiO2|Ti|Ag|TiO2] in which a very thin Ti layer was used as a barrier layer to prevent TiO2 layer from diffusing into Ag layer. The optical constant and thickness of Ag, TiO2, and Ti layers deposited at various sputtering conditions were determined by a variable angle spectroscopic ellipsometer and the transmittance and reflectance of layers were measured by a spectrophotometer to confirm them. A conductive 13-layer NIR cut-off filter was deposited by repeating the basic design four times in a RF magnetron sputtering chamber and the transmittance, reflectance and sheet resistance were measured. The result shows that the photopic average transmittance of the filter was 55 % in the visible and the transmittance beyond 800 nm was under 15%. As the number of period was increased up to four, the sheet resistance and emissivity were decreased as low as 2.75 Ω/sq and 0.035, respectively. Also the experimental measurements will be described in detail.