Effect of mass-selected ion species on structure and properties of diamond-like carbon films

Abstract

Diamond-like carbon (DLC) films were prepared with mass-selected C+, CH2+, CH3+, and CH4+ ions, and the dependence of film microstructures and properties on ion species was investigated with micro-Raman spectroscopy, optical band gap measurement and atomic force microscopy (AFM). The results indicate that highly sp3 bonded DLC films are achieved using carbon and hydrocarbon ions with ion energy of 100 eV. AFM results exhibit that the surface roughness for these films is very low, which is associated with the formation of a dense diamond-like phase as suggested by the subplantation model. The thermal stability of the films were investigated in the temperature region of 200–800 °C. Raman measurements show that the D peak evolves at much lower temperatures for the film prepared with CH4+ than that for the film prepared with C+ ions during annealing. The results indicate that hydrogen-free carbon films have a much better thermal stability than hydrogenated carbon films.