Molecular Dynamics Simulation Of Irradiarion Displacement Damage In Monocrystalline Silicon

Irradiation damage behavior of materials under irradiation conditions is one of the key factors which affect the performance of electronic devices in irradiation environment.The accumulation and evolution of point defects induced by irradiation will lead to the electrical properties changes in the material which have a serious impact on the macroscopic performance of materials.Understranding irradiation damage process and the factors affecting the irradiation is prerequisite for designing irradiation-tolerant materials.In this paper,molecular dynamics simulation is used to study the cascade collision process of silicon in the primary stage of irradiation damage,and the influence of different factors on point defects and clusters generated during irradiation.This paper uses simulation software named of LAMMPS(Large-scale Atomic/Molecular Massively Parallel Simulator).And the existing Tersoff potential function is improved,the Ziegler–Biersack–Littmark potential function suitable for cascade collision simulation is added in the short-range action.Using the improved potential function to study the displacement damagemechanism of Si atom with the primary Knock-on Atom(PKA)incident single crystal silicon.The main work and conclusions are as follows:(1)The irradiation damage process in single crystal silicon was investigated.The silicon atom was selected as the PKA,and the irradiation displacement damage phenomenon of 2 keV incident into the single crystal silicon was simulated at room temperature.The results show that the types of point defects generated by irradiation displacement damage include vacancies and interstitials.The number of Frenkel pairs generated by cascade collisions increases rapidly then decreases,finally reaches the equilibrium value.(2)The effects of different temperatures on the irradiation damage process of Si materials were investigated.The results show that temperature does not affect the law of the number of defects,but it will increase the duration of the cascade collision.Higher temperature lead to greater number of defects at the peak,but the fewer number of defects at the stabilization phase;and the high temperature make more difficult to form large-sized clusters,and the smaller the number of clusters.(3)The effects of different PKA energies on the irradiation damage process of Si materials were investigated.The results show that the number of defects generated by cascade collision is linear with PKA energy,which satisfies the NRT(Norgett-Robinson-Torrens)model.The higher the PKA energy,the more defects will be produced;The higher thePKA energy also lead to larger numbers of clusters and cluster size.(4)The effects of different strains on the irradiation damage process of Si materials were investigated.The results show that under the action of compression,the number of defects will decrease,and under the action of stretching,the number of defects will increase.Under pressure,the cluster size will become smaller,but the number of clusters will increase.