| AVS 54th International Symposium | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | B.M. Howe, University of Illinois at Urbana-Champaign |
| Authors: | B.M. Howe, University of Illinois at Urbana-Champaign J. Bareño, University of Illinois at Urbana-Champaign M. Stoehr, Université de Haute Alsace, France M. Sardela, University of Illinois at Urbana-Champaign J.G. Wen, University of Illinois at Urbana-Champaign J.E. Greene, University of Illinois at Urbana-Champaign L. Hultman, Linköping University, Sweden A.A. Voevodin, Air Force Research Laboratory I. Petrov, University of Illinois at Urbana-Champaign |
| Correspondent: | Click to Email |
Epitaxial metastable Hf1-xAlxN alloys with 0 = x = 0.50 were grown on MgO(001)substrates at 600°C by ultrahigh vacuum reactive magnetron sputtering from Hf and Al targets in 90 % Ar + 10 % N2 discharges at 7 mTorr. X-Ray diffraction and crosssectional transmission electron microscopy show that Hf1-xAlxN alloys are single crystals with the B1-NaCl structure. Rutherford backscattering spectroscopy investigations reveal that all films are slightly overstochiometric with N/(Hf+Al) = 1.05 ± 0.05. The relaxed lattice parameter decreased linearly from 0.4519 nm with x = 0 to 0.4438 nm with x = 0.50, compared to 0.4320 nm expected from the linear Vegard’s rule. We find a metastable single phase field that is remarkably broad given the large lattice mismatch (~ 9 %) between the two alloy components. Alloying HfN with AlN leads to an increase in hardness (~ 30% to 32.4 ± 0.7 GPa), as well as nanostructured compositional modulations due to the onset of spinodal decomposition.