Properties of TiO2 films prepared by the spray pyrolysis method

TiO2 thin films were prepared by spray pyrolysis method. The solution containing titanium(IV)isopropoxide, acetylacetone and ethanol was deposited onto n-type Si(100) and HD Si(100) wafers at substrate temperatures of 315 to 500 degreesC by pulsed spray solution feed. The films were characterized by FTIR, XRD, AFM, ellipsometry, impedance and IN measurements. As-deposited films prepared below 500 degreesC were amorphous, whereas crystalline films could be achieved at 500 degreesC. Subsequent annealing at 700 degreesC in air led to crystalline anatase formation for films deposited below 400 degreesC. Rutile phase appears in annealed films prepared at a growth temperature above 400 degreesC. Anatase TiO2 films show refractive index in the range 2.20 to 2.40 and exhibit a relative dielectric constant value of 75 in the range 1 to 100 kHz. Electric breakdown occurs for 120 nm thick film at 250 kV/cm.