Twin symmetry texture of energetically condensed niobium thin films on sapphire substrate (a-plane Al2O3)
An energetic condensation technique, cathodic arc discharge deposition, is used to growepitaxialNiobium(Nb)thin films on a-plane sapphire (hexagonal-closed-packed Al2O3) at moderate substrate heating temperature (<400 °C). The epitaxial Nb(110)/Al2O3(1,1,-2,0) thin films reached a maximum residual resistance ratio (RRR) value 214, despite using a reactor-grade Nbcathode source whose RRR was only 30. The measurements suggest that the film’s density of impurities and structural defects are lower when compared to Nb films produced by other techniques, such as magnetron sputtering, e-beam evaporation or molecular-beam-epitaxy. At lower substrate temperature, textured polycrystalline Nbthin films were created, and the films might have twin symmetry grains with {110} orientations in-plane. The texture was revealed by x-ray diffraction pole figures. The twin symmetry might be caused by a combination effect of the Nb/Al2O3 three-dimensional epitaxial relationship (“3D-Registry” Claassen’s nomenclature) and the “Volmer-Weber” (Island) growth model. However, pole figures obtained by electron backscattering diffraction (EBSD) found no twin symmetry on the thin films’ topmost surface (~50 nm in depth). The EBSD pole figures showed only one Nb{110} crystal plane orientation. Finally, a possible mechanism is suggested to explain the differences between the bulk (XRD) and surface (EBSD) pole figures.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1021918
- Report Number(s):
- JLAB-ACC-11-1354; DOE/OR/23177-1722; JAPIAU; TRN: US201117%%512
- Journal Information:
- Journal of Applied Physics, Vol. 110, Issue 3; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
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