质子对BaTiO3薄膜辐照损伤的计算机模拟

本文先应用分子动力学模拟BaTiO₃体系在初级击出原子(primary knock-on atom, PKA)轰击下缺陷产生和复合的动力学过程, 模拟结果表明：PKA的方向和能量对缺陷数目有重要影响, 并计算了Ba， O和Ti原子的平均位移阈能分别为69 eV, 51 eV和123 eV, 远大于SRIM程序默认的位移阈能25 eV. 然后应用蒙特卡罗软件包SRIM, 模拟质子在BaTiO₃薄膜中的能量损失过程, 比较位移阈能对模拟结果的影响, 分析质子能量和入射角度对空位数量以及分布的影响. 结果表明空位数量随着质子能量增加而增加, 增加的速率随能量的增加是降低的；当入射角度大于60°, 空位数量随入射角增大而明显减少.

Investigation of proton irradiation damage in BaTiO3 thin film by computer simulation

BaTiO₃ is a kind of perovskite ferroelectric which has the advantages of ferroelectric property, piezoelectric property and radiation resistance. BaTiO₃ thin films and devices have important applications in strong irradiation environment. The structure damage, especially the oxygen vacancy has a crucial influence on the response of ferroelectric under radiation. Molecular dynamics is used to simulate the formation process and the recovery process of defects in BaTiO₃ under the impact of primary knock-on atom (PKA). The results show that the initial motion direction and energy of PKA have significant effects on the number of defects, and the averaged threshold displacement energies of Ba, O and Ti atom are 69 eV, 51 eV and 123 eV respectively. The calculated displacement energy is obviously larger than default value (25 eV) in SRIM code. Furthermore the SRIM code is used to simulate the proton irradiation damage in BaTiO₃ thin film. The results show that the number of vacancy increases with the increase of proton energy, but the increase rate decreases, and the number of vacancy decreases obviously with the increase of incidence angle when it is more than 60°.