Modeling the effects of XFEL irradiation of cadmium sulfide

We investigate the effects of ultrafast XUV/X-ray irradiation on wurtzite and zincblende phases of Cadmium Sulfide using the hybrid XTANT-3 code (1,2). The model addresses nonequilibrium, nonthermal, and nonadiabatic effects, and their interplay (2). Both phases disorder at ~0.5 eV/atom, with melting primarily resulting from electron-phonon coupling, while bandgap collapse is mainly nonthermal. The threshold for atomic disorder is lower than for complete bandgap collapse, which is typical for ionic materials. Disordering involves negative pressures, indicating a higher density for liquid CdS. Classic MD simulations suggest recrystallization and dislocation formation are relevant during the relaxation phase post-irradiation. These findings indicate that, during EUV/x-ray micro(nano)structuring in CdS-based materials, tuning the irradiation dose may allow for controlled transitions between metallic and semiconducting states. 1. XTANT-3. (2023). https://doi.org/10.5281/zenodo.8392569 2. Medvedev, N. XTANT-3: X-ray-induced Thermal And Nonthermal Transitions in Matter theory, numerical details, user manual. doi:10.48550/arXiv.2307.03953.