Field Emission Characteristics of Plasma Enhanced Chemical Vapor Deposited Diamond-Like Carbon Films Using Scanning Probe Measurements

摘要

Field emission characteristics of undoped and nitrogen-doped diamond-like carbon (DLC) films deposited by radio frequency plasma enhanced chemical vapor deposition method were investigated by the scanning probe measurement system specially designed for the micro-scale field emission current measurements. Raman spectroscopy measurement indicated that the intensity ratio of D to G peak (I_D/I_G ratio) increased with negative self-bias voltage. Raman G peak position also shifted to high frequency side. Graphitization of DLC films with increasing both nitrogen doping level and negative self-bias voltage were confirmed by Raman spectroscopy. Electrical conductivity and electron emission also increased significantly with negative self-bias voltage. Inhomogeneous and random distribution of electron emission site was observed from the electron emission mapping performed by scanning the tungsten probe over the film surface under bias conditions from 2000 to 4000 V. Average diameter of emission site increased with bias voltage applied to the probe. Once the high electric field was applied to the low emission site, the emission current increased because of the surface activation. Strong and stable emission characteristics were observed in all samples after activation process.