SURFACE-MORPHOLOGY EXAMINATION OF SOL-GEL DEPOSITED TIO2 FILMS

Thin films of TiO2 were deposited by spin-coating onto both single-poi nt diamond machined (SPDM) disks and mechanically polished disks of al uminum. A titanium alkoxide sol-gel precursor was used and films were heat treated after deposition to remove organic components. This work is being undertaken to analyze the nature of the surface morphology pr oduced by spin-coating, and to examine how the surface morphology can be modified. Detailed analysis of the surface morphology of the films was carried out using atomic force microscopy (AFM). The uncoated surf aces of the SPDM samples show cutting marks characteristic of the sing le-point diamond machining process, while these have largely disappear ed on the coated surfaces. The coatings show some regions where flow l ines are apparent, probably arising from the spinning process, but are otherwise quite featureless, indicating good surface coverage in the spinning process. Line and area scans of the coated surfaces were used to measure the surface roughness. An analysis of measured roughness a s a function of the area of measurement indicates that the measured ro ughness increases with the area of the measurement. This applies to bo th line and area scans. Roughness measurements over macroscopic length s were also carried out with a stylus profilometer and these results a re compared with the AFM measurements. Line scans of the surface profi le of the materials show long wavelength surface features in some of t he samples which are attributed to the diamond machining process.