Computational Materials Science2022，Vol.2039.DOI:10.1016/j.commatsci.2021.111159

Al coverage of AlN(0001) surface and Al vapor pressure - Thermodynamic assessment based on ab initio calculations

Strak, Pawel Ahmad, Ashfaq Kempisty, Pawel Piechota, Jacek Sakowski, Konrad Nowak, Grzegorz Kangawa, Yoshihiro Lazewski, Jan Krukowski, Stanislaw
Computational Materials Science2022，Vol.2039.DOI:10.1016/j.commatsci.2021.111159
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  • NSTL
  • Elsevier

Al coverage of AlN(0001) surface and Al vapor pressure - Thermodynamic assessment based on ab initio calculations

Strak, Pawel 1Ahmad, Ashfaq 1Kempisty, Pawel 1Piechota, Jacek 1Sakowski, Konrad 1Nowak, Grzegorz 1Kangawa, Yoshihiro 2Lazewski, Jan 1Krukowski, Stanislaw1
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作者信息

  • 1. Polish Acad Sci
  • 2. Kyushu Univ
  • 折叠

Abstract

Ab initio calculations were used to determine physical properties of AlN(0001) surface under Al coverage. It was shown that Al atoms are adsorbed in T4 sites for very low Al coverage, up to OAl = 1/4 monolayers (ML). For higher Al coverage, OAl = 1/4ML up to OAl = 1ML the adlayer becomes disordered and corrugated vertically. In this coverage range (0 < OAl < 1ML) the Al bonding energy is independent on the coverage and equal to EDFT ads approximately equal to 5.0eV. For higher coverage, 1ML < OAl 7/6ML, the Al adlayer becomes ordered and atomically flat. The Al adsorption energy in this range is EDFTads approximate to 6.0eV, i.e. much higher. For higher coverage, OAl 1.25ML, the Al adatoms are located in the second layer. The adsorption energy is reduced to EDFT and linearly increasing to EDFT ads = 4.88eV for the coverage increase up to OAl = 2ML. Full thermodynamic analysis identified two regions in equilibrium with Al vapor: first at very low pressures where OAl < 10-3ML and the second for higher pressures which is 1ML < OAl < 7/6ML. The second region is relevant for physical vapor transport (PVT) AlN growth. The nitrogen adsorption process, important for PVT AlN growth, takes place at single or double Al layer covered AlN(0001) surface.

Key words

Aluminum nitride/Surface/Density functional theory/ALUMINUM NITRIDE/EFFICIENT PSEUDOPOTENTIALS/GAN/GROWTH/GAN(0001)/NITROGEN/SILICON/FILMS

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出版年

2022
Computational Materials Science

Computational Materials Science

EISCI
ISSN：0927-0256
参考文献量53
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