[Zurück]

R Hahn, M. Bartosik, M. Arndt, P. Polcik, P.H. Mayrhofer:
"X-Ray nanodiffraction pointing out formation limitations of c-AlN in nanolayered thin films";
Poster: NESY - Workshop: Future Possible Use of Neutron and Synchrotron Sources by the Austrian User Community, Graz; 15.09.2016 - 16.09.2016; in: "Abstract Booklet: Future Possible Use of Neutron and Synchrotron Sources by the Austrian User Community", (2016), S. 42.

Depending on their bilayer period, coherent and cubic CrN/AlN superlattice systems exhibit an exceptional high hardness compared to their single layered constituents. A key factor ensuring these mechanical properties is the epitaxial stabilization of AlN in its metastable cubic (B1) structure, as the thermodynamically stable wurtzite structured AlN formation would lead to a breakdown of coherent growth and subsequent loss of the superlattice effect.
Here we study the formation limitations of c-AlN by conducting cross sectional X-Ray nano-diffraction experiments on a 4 µm thick CrN/AlN multilayer structure with continuously increasing AlN layer thicknesses (1 to 15 nm) on 7 nm CrN layers. The sample was mechanically grinded and polished down to a thickness of about 50 µm. This lamella was scanned in transmission geometry by KB-mirror focused monochromatic synchrotron radiation with an incident energy of 14.9 keV. Our experiments show that coherent growth and consequential columnar grains (over several bilayers) exist for AlN layer thicknesses up to 4 nm. These findings and the microstructure evolution as a function of AlN layer thickness were cross-validated by high resolution TEM investigations.