Microstructure and optical properties of TiO2 thin films deposited at different oxygen flow rates

To research the influence of oxygen flow rate on the structural and optical properties of TiO2 thin film, TiO2 films on glass were deposited by reactive magnetron sputtering. The microstructure and optical properties were measured by X-ray diffractometry, AFM and UV-VIS transmittance spectroscopy, respectively. The results show that the films deposited at oxygen flow rate of 10 mL/min has the lowest roughness and the highest transmittance. The absorption angle shifts to longer wavelengths as oxygen flow rates increase from 5 to 10 mL/min, then to shorter ones as the oxygen flow rate increase from 10 to 30 mL/min. The band gap is 3.38 eV, which is nearly constant in the experiment. For the TiO2 thin films deposited at 10 mL/min of oxyge flow rate, there are nano-crystalline structures, which are suitable for anti-reflection (AR) coating in the solar cells structure system.