Research on gold film-assisted ultraviolet nanosecond laser machining of diamond microgrooves

• A new method of gold film-assisted nanosecond laser machining of single-crystal diamond microgrooves was proposed. • Ablation depth of diamond microgroove reaches a maximum value when gold film thickness increases to 100 nm. • Au-coated diamond has a lower ablation threshold and a higher material removal rate for nanosecond laser machining. • The gold film can enhance laser energy absorption and accelerate diamond graphitization through heat transfer. Diamond microgrooves have great application prospects in biomedicine, high-power semiconductor devices, optical imaging, chip thermal management, and cutting tools. In this work, the effect of gold film on ultraviolet nanosecond laser machining of single-crystal diamond microgrooves was investigated through simulation and experimental research. The simulation results show that the ablation width and depth gradually increase with the increase of gold film thickness, and the ablation depth reaches a maximum value when the thickness of gold film increases to 100 nm. The surface morphology and elemental analysis show that the gold film was first melted and then re-solidified around the microgrooves under ultraviolet nanosecond laser irradiation. The ablation threshold of Au-coated diamond is 4.05 J/cm 2 , 24 % smaller than that of uncoated diamond. The material removal rate of Au-coated microgrooves is always higher than that of uncoated microgrooves at the same laser intensity. At laser intensity of 8.5 J/cm 2 , it is 1.1 times higher than that of uncoated diamond microgrooves. Moreover, the physical mechanism of gold film during laser machining of diamond microgroove is analyzed. This study provides a new method for efficient machining of diamond microgrooves.