Using ab initio molecular dynamics (AIMD), the cascade collision process in GaN irradiated by low‐energy electron beam and the temperature effect on the threshold displacement energy (TDE) are investigated. The temperature effect of the TDE is found to exhibit different patterns for Ga and N primary knock‐on atoms (PKAs). In the considered energy range of initial kinetic energy (40 to 80 eV), displacements induced by Ga PKA show high uncertainty, i.e., the TDE energy strongly depends on the initial configurations, and kinetic energies higher than TDE does not ensure the displacements that form defects. On the contrary, temperature shows relatively small effect on its TDE and displacement induced by N PKAs, which can essentially occur when the PKA kinetic energy is higher than the TDE. Such different effects are possibly due to the different atomic radii of the two elements and the different energy barriers to overcome. Ga PKAs, which have larger atomic radii, are relatively difficult to stabilize in the crystal and tend to relax to its original position with the assistance of thermal vibrations, and vice versa for N PKAs. The simulation results provide a new understanding of TDE and the cascade collisions of PKAs in GaN at finite temperatures, which can be instructive for improving the radiation resistance of GaN devices.

中文翻译：

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低能电子束辐照下温度对 GaN 阈值位移能的影响

利用从头算分子动力学（AIMD），研究了低能电子束辐照下 GaN 的级联碰撞过程以及温度对阈值位移能（TDE）的影响。发现 TDE 的温度效应对 Ga 和 N 初级碰撞原子 (PKA) 表现出不同的模式。在所考虑的初始动能能量范围内（40至80 eV），Ga PKA引起的位移表现出很高的不确定性，即TDE能量强烈依赖于初始构型，高于TDE的动能并不能保证形成的位移缺陷。相反，温度对其 TDE 和 N PKA 引起的位移的影响相对较小，当 PKA 动能高于 TDE 时，基本上会发生这种情况。这种不同的效应可能是由于两种元素的原子半径不同以及需要克服的能量势垒不同造成的。 Ga PKA 具有较大的原子半径，在晶体中相对难以稳定，并且往往在热振动的帮助下松弛到其原始位置，对于 N PKA 反之亦然。模拟结果提供了对有限温度下TDE和GaN中PKA级联碰撞的新认识，这对于提高GaN器件的耐辐射性能具有指导意义。