Elastic constants, Poisson ratios, and the elastic anisotropy of VN(001), (011), and (111) epitaxial layers grown by reactive magnetron sputter deposition.

Elastic constants are determined for single-crystal stoichiometric NaCl-structure VN(001), VN(011), and VN(111) epitaxial layers grown by magnetically unbalanced reactive magnetron sputter deposition on 001-, 011-, and 111-oriented MgO substrates at 430 °C. The relaxed lattice parameter a_o=0.4134±0.0004 nm, obtained from high-resolution reciprocal space maps, and the mass density ρ=6.1 g/cm³, determined from the combination of Rutherford backscattering spectroscopy and film thickness measurements, of the VN layers are both in good agreement with reported values for bulk crystals. Sub-picosecond ultrasonic optical pump/probe techniques are used to generate and detect VN longitudinal sound waves with measured velocities v₀₀₁=9.8±0.3, v₀₁₁±9.1±0.3, and v₁₁₁=9.1±0.3 km/s. The VN c₁₁ elastic constant is determined from the sound wave velocity measurements as 585±30 GPa; the c₄₄ elastic constant, 12663 GPa, is obtained from surface acoustic wave measurements. From the combination of c₁₁, c₄₄, v_hkl, and ρ we obtain the VN c₁₂ elastic constant 178±33 GPa, the VN elastic anisotropy A=0.62, the isotropic Poisson ratio v=0.29, and the anisotropic Poisson ratios v₀₀₁=0.23, v₀₁₁=0.30, and v₁₁₁=0.29. [ABSTRACT FROM AUTHOR]