A refined numerical simulation approach to assess the neutron irradiation effect on the mechanical behavior of wurtzite GaN

TK Li and H Xu and FL Shang, COMPUTATIONAL MATERIALS SCIENCE, 230, 112520 (2023).

DOI: 10.1016/j.commatsci.2023.112520

Neutron irradiation often produces distinct types of damage or defects in gallium nitride (GaN) materials, which could alter the mechanical properties of GaN. This work develops a numerical approach utilizing molecular dynamics (MD) simulation to capture the structural changes and defect evolution characteristics of wurtzite GaN under long-term low- dose neutron irradiation, and to evaluate the variations in fundamental mechanical properties. By comparing different types of potential functions available for describing GaN materials, the Tersoff/ ZBL potential energy function is found to be more suitable for describing the irradiation effects of GaN. A method of using multiple recoil atoms to trigger cascade collision together with a three-stage irradiation process description is proposed to achieve an effective distribution of irradiation defects, as well as to improve computational efficiency. To simulate the irradiation damage accumulation due to successive cascade collisions, it is applicable to apply an iterative process for the simulation model. Using these approaches, uniaxial tension simulations for irradiated wurtzite GaN are performed to analyze the variations in its fundamental mechanical properties along 1 0 1 0 crystalline direction. The results indicate that low-dose irradiation tends to decrease the Young's modulus and tensile strength of wurtzite GaN material, and could alter its deformation mechanisms to some extent.

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