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

Abstract

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)-2 Â 2 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 $0.4 eV, 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 nonreactive 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.

AlGaN UV Detector with Largely Enhanced Heat Dissipation on Mo Substrate Enabled by van der Waals Epitaxy

“…The theoretical calculations in Figure 4e−g demonstrates that the energies for both Mo and Al atoms penetrating through graphene insertion layer are extremely high, reaching up to 17.31 and 15.02 eV, respectively. 28,29 In other words, the insertion of graphene induces high energy barrier for atoms diffusion, therefore, the vdWs epitaxy process triggers the clear and intact epitaxial interface, which provides the prerequisites for the growth of coriented AlGaN crystal.…”