English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Based on recent calculations of the self-diffusion (SD) coefficient inamorphous silicon (a-Si) by classical Molecular Dynamics simulation [M.Posselt, H. Bracht, and D. Radi\'c, J. Appl. Phys. 131, 035102 (2022)] detailedinvestigations on atomic mechanisms are performed. For this purpose twoStillinger-Weber-type potentials are employed, one strongly overestimates theSD coefficient, while the other leads to values much closer to the experimentaldata. By taking into account the individual squared displacements (or diffusionlengths) of atoms the diffusional and vibrational contributions to the totalmean squared displacement can be determined separately. It is shown that thediffusional part is not directly correlated with the concentration ofcoordination defects. The time-dependent distribution of squared displacementsof atoms indicates that in a-Si a well-defined elemental diffusion length doesnot exist, in contrast to SD in the crystalline Si. The analysis of atoms withlarge squared displacements reveals that the mechanisms of SD in a-Si arecharacterized by complex rearrangements of bonds or exchange of neighbors.These are mono- and bi-directional exchanges of neighbors and neighborreplacements. Exchanges or replacements may concern up to three neighbors andmay occur in relatively short periods of some ps. Bi- or mono-directionalexchange or replacement of one neighbor atom happen more frequently thanprocesses including more neighbors. A comparison of results for the twointeratomic potentials shows that an increased three-body parameter only slowsdown the migration, but does not change the migration mechanisms fundamentally.

Atomic mechanisms of self-diffusion in amorphous silicon