Abstract
Spray pyrolysis has been used to deposit (Al2O3)x(TiO2)1-x thin films with controllable properties successfully in this work. The deposition temperatures and the ratios between titanium precursors and aluminum precursors are main parameters controlling film properties, including the refractive index, components of the thin films and the electrical properties. When the deposition temperature is below 380 oC, the refractive index of (Al2O3)x(TiO2)1-x thin films are about 2.2 which is close to refractive index of titanium dioxide. From energy-dispersive X-ray spectroscopy (EDX), the components of (Al2O3)x(TiO2)1-x thin films with various ratio precursors have high content of titanium. As the deposition temperature increases higher than 380 oC, the refractive index of (Al2O3)x(TiO2)1-x thin films are decreasing with the Al precursors increasing. The EDX shows that the molar ratio of titanium and aluminum in thin films are closed to the ratio in the precursor’s solutions. From the lifetime measurement, the higher deposition temperatures have higher lifetime and the lifetime of the (Al2O3)x(TiO2)1-x thin films increase with the contents of aluminum in the thin film increasing. In order to know quality of (Al2O3)x(TiO2)1-x thin film, we implement this dielectric rear surface passivation stack：Al2O3 /(Al2O3)x(TiO2)1-x stack. Comparison from only Al paste for rear stack, our dielectric rear surface passivation stack can increase rear reflectance (at wavelength 1200 nm ) from 25% to 51%. This can be increase short-circuit current, and then increase efficiency.