Hydrogen trapping and stability at the polycrystalline CVD diamond surface and in the subsurface layers

摘要

Diffusion profiles, effusion and x-ray photoelectron spectroscopy experiments are performed on hydrogenated (deuterated) CVD polycrystalline diamond in order to study the location and stability of hydrogen at the diamond surface and in the subsurface layers. The samples, as-grown with deuterium or submitted to deuterium plasma, are then annealed and chemically etched. A thermal treatment at 600 °C modifies the concentration of deuterium accumulated in the subsurface region, while this is not observed by simple chemical etching. The effusion spectra obtained after thermal and chemical treatments show that hydrogen trapped in the subsurface layers is stable up to 700 °C and that the chemical treatment leads to decrease the effusion peak at 860 °C, i.e. the hydrogen trapped at the unface. X-ray photoelectron spectroscopy analyses reveal the evolution of carbon bonding from sp~2 to sp~3. The compete sp~3 bonding is reached after annealing and etching, or after annealing up to 950 °C.