TiO2 thin film coating on a capillary inner surface using atmospheric-pressure microplasma

Titanium dioxide (TiO2) thin films were prepared on a capillary inner surface on a glass chip using plasma-enhanced chemical vapor deposition (PE-CVD) with titanium tetraisopropoxide and oxygen as reactants and helium as the carrier gas at atmospheric pressure. A microplasma was generated inside the capillary with a cross section of 1 × 1 mm2 and a length of 15 mm by radio frequency excitation of 13.56 MHz using externally attached parallel-plate electrodes. After 60 min deposition, transparent thin films were deposited on a capillary inner surface. X-ray photoelectron spectroscopy revealed that the deposited films are in the chemical binding state of TiO2. Scanning electron microscopy images showed that TiO2 thin films have somewhat rough surface with micro/nanoparticles. Typical film thickness was approximately 200 nm. Spatial distribution of the film thickness was also measured by 3 dimensional surface structure analyzer.