Supplemental Material Optical reflectivity and hardness

Supplemental Material Optical reflectivity and hardness

Supplemental Material
Optical reflectivity and hardness improvement of hafnium nitride films via tantalum
alloying
Zhiqing Gu,1 Haihua Huang,1 Sam Zhang,2 Xiaoyi Wang,3 Jing Gao,1 Lei Zhao,1
Weitao Zheng1, 4, * and Chaoquan Hu1, *
1
School of Materials Science and Engineering, State Key Laboratory of Superhard Materials,
and Key Laboratory of Automobile Materials of MOE, Jilin University, Changchun 130012, China
2
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50
Nanyang Avenue, Singapore 639798, Singapore
3
Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute
of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
4
State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun
130025, China
*Corresponding authors. E-mail: [email protected] (W. T. Zheng); [email protected] (C. Q. Hu);
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FIG. S1. The measured and fitted reflectivity spectra of Hf1-xTaxN films with x = 0 (a), 0.03 (b), 0.06
(c), 0.11 (d), 0.26 (e) and 1.00 (f).
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FIG. S2. Central energy E0, strength S, and width Γ in the (a) high-energy (OH) and (b) low-energy
(OL) Lorentz oscillators and (c) Drude parameters including relaxation time τ, plasma energy Ep,
dielectric constant ε∞ for Hf1-xTaxN films with different x. For the sake of comparison, the energy
positions of two peaks occurring in the DOS spectra obtained by first-principles calculations are
also shown.
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FIG. S3. The (a) measured cutoff wavelengths at the minimum reflectance (λRmin) for Hf1-xTaxN
films with different x, and the (b-j) simulated λRmin obtained at different Drude and Lorentz
parameters.
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FIG. S4. The (a) measured reflectance in the infrared region (RIR) for Hf1-xTaxN films with different
x, and the (b-j) simulated RIR obtained at different Drude and Lorentz parameters.
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FIG. S5. Five models for HfN, Hf3TaN4, Hf2Ta2N4, HfTa3N4 and TaN structure.
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FIG. S6. The (a) hardness and (b) elastic modulus for Hf1-xTaxN films with different x.
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