Chemical vapor deposition of TiO2 thin films from a new halogen-free precursor

TiO2 films are synthesized by chemical vapor deposition using the recently synthesized precursor Ti(H3BNMe2BH3)2 with H2O as the co-reactant. Films grown between 350 and 450 °C are crystalline and consist of a mixture of rutile and anatase phases; the fraction of rutile/anatase is larger at 450 °C. The films are continuous, dense, and pure, with the sum of B, C, and N impurities <1 at. %. The growth rate is ∼1.2 nm/min, limited by the precursor feed rate and therefore independent of temperature. The growth rate decreases monotonically with increasing H2O pressure due to the competition between precursor and co-reactant molecules for adsorption sites on the surface. The advantages of this system compared with other available Ti-bearing precursors are the absence of halogen and the synthesis of mixed-phase material at modest temperatures.