Molecular Simulations on Threshold Displacement Energy in Amorphous Tantalum Pentoxide

L Li and XC Chen and GX Yang and G Zeng and XQ Liu and XF Yu, IEEE TRANSACTIONS ON NUCLEAR SCIENCE, 72, 3717-3725 (2025).

DOI: 10.1109/TNS.2025.3629416

Amorphous tantalum pentoxide (Ta2O5)-based resistive memory devices are sensitive to displacement damage from energetic particles. Energetic particles can displace atoms to produce oxygen vacancies in the oxide. Conductivity of the resistive devices increases with the increase in the density of oxygen vacancies, as these vacancies are responsible for the electron transport through the oxide. The displacement behaviors of tantalum and oxygen atoms in Ta(2)O(5 )films are studied in detail using molecular simulations. Then, the threshold displacement energies of the two spices of atoms are extracted from the simulation data to calculate the density of atom vacancies from displacement damage. Moreover, an analytical model based on Poole-Frenkel mechanism is proposed to calculate the current formed by oxygen vacancies. The model provides a good fit to the previous experiments for the degradation of off-state resistance ( R-OFF ) for Ta2O5-based resistive devices subjected to 800-keV tantalum ions. This model also suggests a linear relationship between the change in the reciprocal of the sixth root of R-OFF ( Delta ( 1(6)root R-OFF ) and the ion fluence ( Phi ), i.e., Delta ( 1/(6)root R-OFF) proportional to Phi .

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