Preparation and structural evolution of TiO2 thin films by low pressure MOCVD

Titanium dioxide thin films were prepared by low pressure metal organic chemical vapor deposition (LP-MOCVD) from titanium IV isopropoxide. Nitrogen was used as a carrier gas for the titanium precursor, and oxygen as a reactant gas. The deposition rates of the films have been studied as functions of process parameters such as substrate temperature and oxygen flow rate. Structural evolution of the films has been studied as functions of substrate temperature (110 to 700°C) and annealing temperature. The films have been characterized by X-ray diffraction and by Raman scattering. Films deposited onto Si(100) substrates were amorphous at 110-250°C, anatase at 350-550°C and rutile above 650°C. The films deposited at substrate temperatures less than 550°C and annealed at 600°C for two hours were anatase, annealed at 700°C for two hours were mixtures of anatase and rutile, and annealed at 850°C for two hours were rutile.