Inorganic-Filler Chemical Vapor Deposition: A New Approach To Grow Nanoporous Thin Films
نویسندگان
چکیده
A new method for the growth of nanoporous thin films is described. The process is targeted to the formation of titanium dioxide (TiO2) through a low-temperature inorganic-filler chemical vapor deposition (CVD) process. The growth technique employs gas-phase reaction of an alkali metal (Na) and a metal halide (TiCl4) and subsequent thin film growth within a low-pressure coflow diffusion reactor. Titanium and salt were codeposited from the gas phase on a heated graphite substrate placed within the reaction zone. After deposition, salt was removed from the surface through a water rinse, yielding a nanoporous structure. The remaining thin film was oxidized to yield titanium dioxide. Qualitative analysis of surface nanostructure and quantitative analysis of pore characteristics showed that the films contained TiO2 in both anatase and rutile phases, with porosities ranging between 55 and 67%. The dependence of film thickness and pore characteristics on reactant velocity, substrate temperature, and reactant concentration are presented. The synthesis scheme should be generic to the formation of a wide variety of metal and metal oxide porous thin films.
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