Probing the displacement damage mechanism in Si, Ge, GaAs by defects evolution analysis

Abstract With the rapid development of space technology, the requirements for the radiation resistance of solar cells are higher and higher. A clear understanding of the radiation damage mechanism of materials is very important for radiation hardening of space solar cells. Therefore, molecular dynamics (MD) method was utilized to simulate the irradiated defects evolution in mainly used materials (Si, Ge, and GaAs) for multi-junction solar cells. By simulating the cascade collision process took placed in different materials under different interatomic potential, it is determined that Tersoff potential was more suitable for radiation damage simulation of semiconductor materials. By comparing the number of Frenkel pair defects (FPs) produced in the three materials during irradiation, the radiation resistance of each material was obtained. The MD results were verified by comparing with empirical NRT model. The displacement evolution of off-site atoms and the final clusters formed by point defects, i.e. interstitials and vacancies were further quantitatively analyzed. The atomic image of irradiated defects provides new physical insights for displacement damage mechanism and gives better understanding for explaining the degradation of irradiated multi-junction solar cells.