Abstract: The Cu-doped diamond-like-carbon(DLC) films were deposited on the Cu-substrate,coated with TiC/Ti transition layers,in the self-developed coating reactor.The influence of the Cu-doping on the field emission characteristics and microstructures was investigated with scanning electron microscopy and Raman spectroscopy.The preliminary results show that Cu-doping had a major impact.To be specific,as the Cu-content increased,the density of irregularly shaped "sub-micro cusp" changed in an increase-decrease-vanish mode,and the conductivity of Cu-doped DLC coating increased because of the increase of sp² and Cu surface densities,bringing about an enhancement-deterioration of the field emission behavior.For example,the optimized Cu-doping decreased the emission onset field to 40 V/μm,5 V/μm lower than that of the undoped DLC-sample.However,an over-doping of Cu deteriorated the field emission properties.