Growth and characteristics of diamond-like carbon (DLC) films deposited by direct negative carbon ion beam deposition

Abstract

Diamond-like carbon films were deposited on Si substrate using direct negative carbon ion (C−) beam source at various C− ion beam energy and then the effect of ion beam energy on the crystal structure, sp3/sp2 ratio, hardness and surface roughness of DLC film was investigated. As ion beam energy increased from 25 to 150eV, the sp3/sp2 ratio of DLC films increased from 32% to 67%.The films prepared at 150eV showed the more flat surface morphology of the film than that of the film prepared under another ion beam energy conditions and diamond structure also obtained at 150eV. Surface roughness of DLC film varied from 0.62 to 0.22nm with depositing carbon ion beam energy. The film prepared at 50eV shows the typical amorphous phase, while the films prepared at 150eV exhibited (111) plane of diamond. Nanohardness increased from 12 to 57GPa when increasing the negative carbon ion beam energy from 25 to 150eV and then decreased above 150eV.