A new method to characterizing surface roughness of TiO2 thin films

Titanium dioxide (TiO2) thin films have been widely coated in the self-cleaning glass for facade application. The benefit of these glasses is its ability to actively decompose organic compounds with the help of ultraviolet light. Understanding the surface roughness of TiO2 thin films is important before manufacturing of self-cleaning glasses using TiO2 thin films because surface roughness of TiO2 thin films has highly significant influence on the photocatalytic performance. Traditional approach for measuring surface roughness of TiO2 thin films is atomic force microscopy. The disadvantage of this approach include long lead-time and slow measurement speed. To solve this problem, an optical inspection system for rapidly measuring the surface roughness of TiO2 thin films is developed in this study. It is found that the incident angle of 60° is a good candidate for measuring surface roughness of TiO2 thin films and y=90.391x+0.5123 is a trend equation for predicting the surface roughness of TiO2 thin films. Roughness average (Ra) of TiO2 thin films (y) can be directly determined from the peak power density (x) using the optical inspection system developed. The results were verified by white-light interferometer. The measurement error rate of the optical inspection system developed can be controlled by about 8.8%. The saving in inspection time of the surface roughness of TiO2 thin films is up to 83%.

Research highlights► The measurement error rate of the optical inspection system developed can be controlled by about 8.8%. ► The saving in inspection time of the surface roughness of TiO2 thin films is up to 83%. ► Roughness average (Ra) of TiO2 thin films (y) can be directly determined from the peak power density (x) using the optical inspection system developed.