Preparation of diamond-like carbon films by high-intensity pulsed-ion-beam deposition at room temperature

Diamond-like carbon (DLC) films were prepared onto Si (100) substrates at room temperature by high-intensity pulsed-ion-beam (HIPIB) ablation of graphite targets. A 250 W, 250 A.cm(-2), 80-100 ns beam, consisting primarily of hydrogen and carbon ions, was focused onto a graphite target at a flux of 5 J.cm(-2). The graphite surface was rapidly heated, causing vaporization and ionization, resulting in an plume. The plume expanded outward in a direction normal to the graphite surface, and subsequently condensed onto a Si substrate, which was placed in the path of the plume. Raman spectra analysis demonstrates the DLC film was synthesized. With decreasing substrate/target distance, the sp(3) C content in the films increased, at the same time knoop microhardness increased, and the surface roughness and friction coefficient also increased. The analysis of the x-ray photoelectron spectra (XPS) of C1s core level of the thin films shows the sp(3)C content in the films is about 40%. Scanning electron microscope and Atomic force microscopy indicates that the DLC films are smooth and the surface roughness is lower. Microhardness is between 24 and 30 GPa. Friction coefficient is between 0.16 and 0.38.