Surface chemical modification of CVD diamond films by laser irradiation

摘要

The wettability of CVD diamonds, which much depends on the surface chemical state, is of great importance to their applications. In this work, surface chemical modification of diamond films are performed with nanosecond (ns) laser irradiation in ambient air, and the influence of chemical modification on the wettability of diamond films is investigated. Two types of laser fluence, namely fluence above ablation threshold and fluence between ablation threshold and graphitization threshold are used. The surface morphology and chemical composition of irradiated diamond films are characterized by scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman scattering analysis and X-ray photoelectron spectroscopy (XPS), respectively. Graphitization, oxidation and nitridation on CVD diamond surface can be clearly observed for both fluences. Angle contact measurements show that after such evolution of surface terminations super-hydrophilic properties can be obtained. Besides, the fluence between ablation threshold and graphitization threshold appears to be more preferable, for the surface graphitization with such fluence is much slighter in comparison with the fluence above ablation threshold. This is of great importance to the bioimplantable application of CVD diamond films.