Simulation of defect formation, amorphization and cluster formation processes in nc-TiN/a-Si3N4 nanocomposite under Xe irradiation

Abstract

The research of defect formation and clusterization processes by means of a molecular dynamics method both in nc-TiN nanocrystals and amorphous a-Si3N4 matrix, as the constituents of nc-TiN/a-Si3N4 nanocomposite, under exposure to Xe implantation was the aim of the present study. Dependences of the clustered Xe atoms fraction on their concentration and temperature of post-irradiation annealing were analyzed. At defect formation process in nc-TiN nanocrystals, there is a size effect consisting in intensification of the radiation point defects formation with the reduction of nc-TiN nanocrystals size and concurrent predominant formation of the dangling Si- and N-bonds in a-Si3N4 matrix. Accumulation of these defects at the irradiation leads to amorphization of nc-TiN nanocrystals with the size less than 8 nm and to formation of the nanopores in a-Si3N4 matrix. The important role of the radiation defects subsystem in transport processes of implanted Xe both in TiN close-packed lattice as well as in a-Si3N4 amorphous matrix is shown. There is a much higher extent of intensity of xenon atoms clusterization processes in the amorphous matrix. The results of the simulation are compared to existing experimental data.