Study on ultraviolet laser processing of a single-crystal diamond along 〈1 0 0〉 and 〈1 1 0〉 crystal orientations

Single-crystal diamond has been widely used in precision cutting tools, micro-electronic devices, optical devices and biological fields. In this work, microgrooves were created on single-crystal CVD diamond {1 0 0} surfaces along 〈1 0 0〉 and 〈1 1 0〉 crystal orientations by an ultraviolet nanosecond laser. Experiment results revealed that the surface morphology within microgrooves, the ablation rate, and the material removal rate were found to be strongly dependent on crystal orientation. Microgrooves along 〈1 1 0〉 crystal orientation have better inner surface morphology and higher material removal rate than microgrooves along 〈1 0 0〉 crystal orientation. The difference in material removal rates of microgrooves along 〈1 0 0〉 and 〈1 1 0〉 orientations was explained. Raman analysis revealed that the attached nanoparticles within microgrooves were graphite, and the thickness of graphite layer on the sidewall of 〈1 1 0〉 microgrooves was thinner than that of 〈1 0 0〉 microgrooves. Transmission electron microscopy analysis expressed that the ablation products of diamond contained disordered graphite and nanocrystalline diamond. Therefore, these results could provide significant guidance for laser processing of diamond microgrooves.