One-step synthesis of a carbon nano sheets-carbon nanotubes composite by plasma enhanced chemical vapor deposition and its field emission properties are investigated. We obtain the carbon nano sheets-carbon nanotube composite on the Co thin film with 20 nm Ti interlayer. We gain carbon nano sheets only on the Co thin films without Ti interlayer in the same growth conditions. The carbon nano sheets are distributed on the side wall and the top of carbon nanotubes. The Ti interlayer hinders the diffusion of Co...