N and Ti adatom dynamics on stoichiometric polar TiN(111) surfaces

SURFACE SCIENCE

卷:649

Article

Sangiovanni, D. G.¹  Tasnadi, F.¹  Hultman, L.¹  Petrov, I.^1,2,3  Greene, J. E.^1,2,3  Chirita, V.¹ 

[1] IFM Linkoping Univ, Dept Phys Chem & Biol, SE-58183 Linkoping, Sweden

[2] Univ Illinois, Dept Mat Sci, Phys, Urbana, IL 61801 USA

[3] Univ Illinois, Frederick Seitz Mat Res Lab, Urbana, IL 61801 USA

关键词: Surface diffusion;    Nitrides;    Molecular dynamics;    Density functional theory;    Polar surfaces;   

DOI  :  10.1016/j.susc.2016.01.031

来源: Elsevier

【 摘 要 】

We use molecular dynamics (MD) based on the modified embedded atom method (MEAM) to determine diffusion coefficients and migration pathways for Ti and N adatoms (Ti-ad and N-ad) on TiN(111). The reliability of the classical model-potential is verified by comparison with density functional theory (DFT) results at 0 K. MD simulations carried out at temperatures between 600 and 1800 K show that both Ti-ad and N-ad favor fcc surface sites and migrate among them by passing through metastable hcp positions. We find that N-ad species are considerably more mobile than Ti-ad on TiN(111); contrary to our previous results on TiN(001). In addition, we show that lattice vibrations at finite temperatures strongly modify the potential energy landscape and result in smaller adatom migration energies, E-a = 1.03 for Ti-ad and 0.61 eV for N-ad, compared to 0 K values E-aOK = 1.55 (Ti-ad) and 0.79 eV (N-ad). We also demonstrate that the inclusion of dipole corrections, neglected in previous DFT calculations, is necessary in order to obtain the correct formation energies for polar surfaces such as TiN(111). (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

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