Ti adatom diffusion on TiN(001): Ab initio and classical molecular dynamics simulations
2014 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 627, 34-41 p.Article in journal (Refereed) Published
Ab initio and classical molecular dynamics (AIMD and CMD) simulations reveal that Ti adatoms on TiN(001) surfaces migrate between neighboring fourfold hollow sites primarily along in-plane less than100greater than channels. less than100greater than and less than110greater than single jumps, as well as less than100greater than double jump rates, obtained directly from MD runs as a function of temperature, are used to determine diffusion activation energies Ea, and attempt frequencies A, for the three preferred Ti adatom migration pathways on TiN(001). From transition rates Aexp[-Ea / (k(B)T)], we determine adatom surface distribution probabilities as a function of time, which are used to calculate adatom diffusion coefficients D(T). AIMD and CMD predictions are consistent and complementary. Using CMD, we investigate the effect on the adatom jump rate of varying the phonon wavelength degrees of freedom by progressively increasing the supercell size. We find that long-wavelength phonons significantly contribute to increasing adatom mobilities at temperatures less than= 600 K, but not at higher temperatures. Finally, by directly tracking the Ti adatom mean-square displacement during CMD runs, we find that Ti adatom jumps are highly correlated on TiN(001), an effect that yields lower D-s values (D-s(corr)) than those estimated from uncorrelated transition probabilities. The temperature-dependent diffusion coefficient is D-s(corr) (T) = (4.5 x 10(-4) Cm-2 s(-1)) exp[-0.55 eV / (k(B)T)].
Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 627, 34-41 p.
Surface diffusion; Nitrides; Molecular dynamics simulations; Density functional theory
IdentifiersURN: urn:nbn:se:liu:diva-109215DOI: 10.1016/j.susc.2014.04.007ISI: 000338621500006OAI: oai:DiVA.org:liu-109215DiVA: diva2:737206