This study examined growth of single-walled carbon nanotubes （SWCNTs） by hot-filament chemical vapor deposition at low temperatures using a double-layer film consisting of iron and cobalt layers as a catalyst. Ethanol was used as the carbon source. At a 350 ℃ growth temperature, few SWCNTs were grown when only cobalt film was used as the catalyst, although SWCNT growth was confirmed when a double-layer film consisting of iron and cobalt layers was used as the catalyst. The optimal combination for use as the catalyst is iron oxide in a layer （thickness before oxidation, 1.2 nm） on the cobalt oxide in a layer （thickness before oxidation, 1.0 nm）. By reduction of these films at 400 ℃ for 30 min, followed by CNT growth at 350 ℃ for 30 min, a vertically aligned SWCNT film with 3.2 μm thickness was obtained.
