Field emission properties of carbon nanocoils synthesized on stainless steel

Carbon nanocoils (CNCs) were synthesized by a thermal chemical vapor deposition (CVD) method over tin-coated type 202 stainless steel (SS) plates (Cr 15%, Mn 10%, Ni 1%). It is considered that the calcination at 900 °C leads to the crazing of the SS surface, which causes the Fe (Ni) and Sn to be fully mixed and forms active Fe (Ni)-Sn-O catalyst particles suitable for the growth of CNCs. However, the Cr in the catalyst particles is below the limitation of detection, and its role is currently not understood. The electron field-emission properties of as-grown CNCs dispersed on an n-type Si substrate were also investigated. It is found that the CNCs exhibit a low turn-on electric field of 1.6 V/m. The distributions of electric fields on a stand-up and a laid-down CNC successfully explain the behavior of the Fowler-Nordheim (F-N) plot. The field enhancement factor for the laid-down CNC is 2.25 times larger than that for a laid-down multiwall carbon nanotube (CNT). This is because the helical morphology of the CNCs can reduce the screening effect produced by the surrounding substrate. In this case, CNCs can more easily emit electrons, and show promise for use in X-ray sources, field emission displays and other micro- or nano-devices.