Etching effects of hydrogen plasma treatment on diamond surfaces

Hydrogen plasma was employed to etch the surfaces of diamond films under various sputtering time. After hydrogen plasma treatments, the surface morphologies and phase structures of diamond films were investigated by scanning electron microscopy, atomic force microscopy, three-dimension white light interferometer, X-ray photoelectron spectroscopy and Raman spectroscopy, respectively. The results showed that the etching mainly concentrates on the crystal grains at the early stage. Many steps, pits, together with abundant subgrains, appear on the surface of the diamond crystalline. At the same time, the surface roughness decreases. At this stage, etch of sp3 phase is prior to that of sp2 phase. When the sputtering time prolongs, the sculpture of grain boundaries begin to accelerate. At this stage, the surface roughness increases and the sp2 phase is etched much faster than the sp3 phase.