Laser-assisted etching of diamonds in air and in liquid media

Etching of both synthetic diamond monocrystals and diamond polycrystalline films has been studied with the help of a copper vapor laser (wavelength of 510 nm, pulse duration of 10 ns, pulse repetition rate of 8 kHz) in various surrounding media (air, H2O, DMSO). Diamond samples are virtually transparent in this wavelength and the coupling of laser radiation to diamond is due to the formation of a thin graphitized layer at the diamond surface. The etching rate in liquid media is slightly higher than in air, at otherwise equal conditions, and is as high as 50 μm s −1 under the etching with a scanning laser beam. Raman spectra measurements carried out on diamond samples etched in air show the presence of glassy carbon on the surface, while under the etching in a liquid the diamond peaks at 1332 cm−1 and dominates with significantly lower intensity of the glassy carbon peak. Electroless copper deposition on the laser-etched features was studied to compare the catalytic activity of the diamond surface etched in air with the catalytic activity of the surface irradiated in liquids. Possible mechanisms responsible for the observed difference both in the structure of the etched area and in the electroless Cu deposition onto the surface etched in various media (air or liquids) are discussed.