Field emission from diamond-like carbon films deposited using RF inductively coupled CH{sub}4-plasma source

摘要

Diamond-like carbon (DLC) films 4-400 nm thick were deposited on conductive u-Si and metalsubstrates using direct ion beam deposition from an RF inductively coupled CH{sub}4-plasma (ICP)source. The field electron emission of the films was examined as a function of deposition conditionsand post-deposition surface modification by Ni ultrathin coatings. Electrical properties of the filmswere studied as well. A specially designed high vacuum scanning tunnelling-field emissionmicroscope was employed for simultaneous mapping of the topography, work function and local fieldelectron emission intensity. Stable, low voltage emission was observed after the emission electricfield/current activation process. The activation mechanism was probably the formation of conductivechannels in the films to supply electrons for emission from low work function surface areas.Deposition of ultrathin metal coatings on the DLC films reduced both the effective barrier height andthe field emission threshold. The DLC films surface coated with ultrathin Ni films resulted in electronemission at fields as low as 20-25 Vμm{sup}-1. It was shown that DLC films with thicknesses inthe range 5-15 nm demonstrated efficient field emission long-term stability. The results areinterpreted based on the reduced electrical resistivity of nanometer scale thick films, and deviation ofresistivity over the surface.