ABSORPTION AND THERMAL-CONDUCTIVITY OF OXIDE THIN-FILMS MEASURED BY PHOTOTHERMAL DISPLACEMENT AND REFLECTANCE METHODS

Photothermal reflectance and photothermal displacement measurements of optical absorption and thermal conductivity are reported for electron-beam- (EB) deposited and ion-plated (IP) thin films of TiO2, Ta2O5, and ZrO2. Of the particular set of samples investigated, the EB films have higher absorption than the IP films. The absorption of the EB samples decreases over a period of approximately 90 min on irradiations with an Ar-ion laser of 488-nm wavelength. By contrast, the absorption of the IP samples changes insignificantly or not at all. Photothermal displacement area scans of coating surfaces yield lower defect densities for the IP samples compared with the EB samples for al three oxide materials. The feasibility and limitations of photothermal measurements for thin-film optical and thermal characterizations are discussed.