Atomistic simulations on the relationship between solid-phase epitaxial recrystallization and self-diffusion in amorphous silicon

Recent experimental results on self-diffusion (SD) in amorphous silicon (a-Si) [Kirschbaum et al., Phys. Rev. Lett. 120, 225902 (2018)] indicate that the atomic mechanism of this process is akin to that of solid-phase epitaxial recrystallization (SPER). In the present work, this relationship is investigated using classical molecular dynamics (MD) simulations with selected interatomic potentials. In the beginning, an overview of the status of the present knowledge on SPER and SD is given. Then, it is shown that the Stillinger-Weber (SW)-type and Tersoff (T)-type potentials considered yield structural data of a-Si, which are in rather good agreement with measurements. On the other hand, deviations are found for thermal properties. The results of partially extremely long MD calculations of SPER and SD yield that both processes can be described by a simple Arrhenius relation and that the activation enthalpies of SPER and SD are rather equal, which is in qualitative agreement with experiments. Obviously, the simulated atomic-level processes are very similar. However, for the known SW- and T-type interatomic potentials, a quantitative agreement with SPER and SD measurements cannot be found. This work demonstrates that significant improvements can be achieved if SW-type potentials with an increased value of the three-body parameter are used.