Interface structural stability of Zr on the AlN (0001) surface: An ab-initio study

• Published in: Physica Status Solidi. B: Basic Solid State Physics 2013-08, Vol.250 (8), p.1526-1531
• Main Authors: Escorcia-Salas, Gene E, Rivera-Julio, Jagger, Lopez-Perez, William, Gonzalez-Hernandez, Rafael, Sierra-Ortega, Jose
• Format: Article
• Language: English
• Subjects: Adsorption
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201248541

Ab-initio density functional theory calculations are carried out to investigate the role of zirconium (Zr) impurity atoms during AlN(0001) surface growth. Adsorption and diffusion of Zr atoms on AlN(0001)-22 surface is examined and it is shown that Zr atoms preferentially adsorb at the T4 sites at low and high coverage (from 1/4 up to 1 monolayer). We found that the Zr adatom diffusion energy barrier between the T4 and H3 sites is around 0.4eV, which is an indication of a significant Zr adatom diffusion on this surface. In addition, calculating the relative surface energy of several configurations and various Zr concentrations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the Zr and Al chemical potentials. Based on these results, we find that incorporation of Zr adatoms in the Al-substitutional site is energetically more favorable compared with the adsorption on the top layers. This effect leads to the formation of a non-reactive interfacial ZrN(111) layer on the AlN(0001) surface, which can offer a good interfacial combination between AlN substrate and other metal contacts, i.e. zirconium.