Characterization of UV irradiated nanocrystalline diamond

The exposure of H-terminated nanocrystalline diamond (NCD) to ultraviolet (UV) light in air and at room temperature modifies the features of the diamond surface, in terms of wettability, electrical conductivity and chemical reactivity. This allows the development of a soft, dry and non invasive method to tailor the surface properties for the development of new chem- or bio-sensors. In this work, we report about the analysis of hydrogen terminated nanocrystalline diamond films grown by hot-filament technique and of their surface modification following UV light exposure. This UV treatment induces an hydrophobic to hydrophilic transformation and an outstanding increase of the electrical resistivity (> 105). X-ray (XPS) and ultraviolet (UPS) photoelectron spectroscopy provide insight into the role of chemisorbed oxygen on the modification of the valence band and on the transformation of the electron affinity (from negative to positive) at the diamond surface.