Growth and Properties of TiCl₄‐Derived CVD Titanium Oxide Films at Different CO₂/H₂ Inputs

Abstract

Crystalline titanium oxide films with a thickness of 0.09±0.55 lm were prepared at temperatures below 500 C by CVD using a mixture of titanium tetrachloride (TiCl 4 ), carbon dioxide (CO 2 ), and hydrogen (H 2 ) as reactants. Film thickness decreased with increasing substrate temperature and CO 2 /H 2 input. Nanosized microstructure was obtained at high CO 2 /H 2 input due to the growth retardation of reacted HO-TiCl 3 * by the unreacted TiCl 4 and CO 2 . That film composition, i.e., the O/Ti ratio, increased with temperature and the CO 2 /H 2 input can be explained by growth kinetics. Unlike film thickness, internal film stress increased with increasing substrate temperature. Adhesion was controlled by compressive internal stress due to the weak bonding between film and substrate. Two growth mechanisms are proposed to explain the tensile and compressive stress states in films produced by CVD. The adsorption-controlled reaction has a film in compressive stress that increases with an increase in temperature. On the other hand, thermally activated CVD produces a film in tensile stress that decreases with an increase in substrate temperature.

Properties of CVD alumina–titania composite films grown at different CO2/H2 inputs

“…Furthermore, the occurrence of the compressive internal stress corresponds to the growth kinetics. It has been proposed for depositing CVD films that the compressive stress is developed for the adsorption-controlled reaction, while the tensile stress is induced for the thermally activated reaction [27]. The film adhesion was evaluated by the scratch test and the specific critical load was defined.…”

“…Crystalline TiO 2 in an anatase phase can be obtained at 350°C with the TiCl 4 / CO 2 /H 2 system [27]. Al 2 O 3 with high melting temperature has been known for its difficulty in crystallization.…”

Growth and properties of chemical-vapor-deposited Ti–P–O films grown under the CO2- and H2-existing conditions

“…Under the HCl environments, the reaction between P(O-CH 3 ) 3 and HCl occurs and the P-Cl bonding forms by reaction (5). The formed P-Cl bonds have a difficulty in reacting with TiCl 4 or TiCl 3 adsorbates to form the Ti-O-P bonding, but are capable of forming the P-O-P bonds by reacting with P-(O-CH 3 ).…”

“…Deposition of the TiO 2 thin films by chemical vapor deposition (CVD) at different CO 2 /H 2 flow inputs has been started in our group [5]. Based upon the deposition of CVD-TiO 2 with the TiCl 4 /CO 2 /H 2 system at and below 500°C, it has been observed that the CO 2 /H 2 input has effects on grain size, growth rate, composition, film internal stress, and electrical and dielectric properties.…”

Photosensitized and photocatalyzed degradation of azo dye using Lnn+-TiO2 sol in aqueous solution under visible light irradiation

“…So far, a variety of physical and chemical approaches have succeeded to synthesize anatase and rutile TiO 2 catalysts, including sputtering synthesis [4], flame pyrolysis [5], electrochemical deposition [6], chemical vapor deposition [7], precipitation [8], and sol-gel methods [9]. However, the physico-chemical properties of the synthesized TiO 2 particles are significantly affected by the precursor used and the preparation procedure applied.…”