An atomistic investigation of FIB process damage on diamond

Focused Ion Beam (FIB) is one of the important machining techniques to fabricate diamond sensors/detectors used for drug analysis, chemical analysis and bio-sensing applications. In-depth understanding of the high energy collision process and the residual damage induced along the trace of gallium ion could undoubtedly facilitate the development and improvement of performance of such devices through the optimization of machining processes. Based on the merit offered by large-scale molecular dynamics (MD) simulation method and the new progress made in high performance computing technique (HPC), a new atomistic modelling system was proposed in this paper to investigate the high energy collision process involved two gallium ions. The simulation results indicated that the energetic ion collision process comprises a bombardment event with a pulse temperature and a lateral relative long period annealing recrystallization process. The peak temperature for the second ion collision was 129.2 K higher than the first one, which indicates the alternation of the thermal conductivity of diamond due to the formation of amorphous (sp2 graphite-like) structure during the first ion collision and annealing process. Besides giving the damage configuration and distribution in diamond after fully recrystallization, the simulation also used coordination number (CN) and radius distribution function (RDF) to revel the change of diamond lattice structure after the collision process, which provided an insight of damage induced by FIB process.