Research on laser-induced Plasma-Assisted ablation of single crystal Diamond: Experiment and molecular dynamics simulation

Abstract

Traditional machining methods face significant challenges in removing and processing diamond due to its high hardness, brittleness and wear resistance. A promising solution is laser-induced plasma-assisted ablation (LIPAA), which has gained attention as a reliable technology for processing transparent, hard and brittle materials, especially diamond. However, the complexity of the machining mechanism of LIPAA limits its widespread application. This study aimed to investigate the characteristics of LIPAA processing on diamond through experimental and simulation analysis. The experimental results revealed that the amorphization threshold of laser energy density is 3.36 J/cm², the deposition threshold is 3.89J/cm², and the etching threshold is 4.07 J/cm². When employing an infrared laser with a repetition rate of 115 kHz, the range of laser single pulse energy for LIPAA etching on single crystal diamond is from 115μJ to 145μJ, the range of the laser energy density is from 4.07 J/cm².to 5.13 J/cm². In addition, the width, depth and material remove rate of the diamond microgrooves increases with the increasing laser energy. A simulation model employing molecular dynamics (MD) technology was developed to examine the impact of copper plasma bombardment on single crystal diamond. The simulation results show that the deposition velocity threshold of copper ion bombardment on single crystal diamond is 1.062 × 10⁴ m/s, while the etching velocity threshold is 1.143 × 10⁴ m/s. The degree of amorphization on the diamond surface increased with the increase of bombardment speeds and system temperatures. The morphology, element distribution, and the graphite layer quality of the microgrooves were analyzed, and the formation mechanism of the microgrooves was explored. By combining experiments and simulations, it is concluded that the mechanism of LIPAA processing single crystal diamond is the formation of amorphous regions on the diamond surface by ion bombardment, while high-energy laser beams and plasma ablate the amorphous regions to form grooves.