Modulation periodicity dependent structure, stress, and hardness in NbN/W{sub 2}N nanostructured multilayer films

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3598083· OSTI ID:21538443

Wen, M; Tian, H W; Hu, C Q; Zeng, Y; Meng, Q N; Zhang, K; Zheng, W T ^[1]; An, T ^[2]; Zou, G T ^[3]

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1. Department of Materials Science, Key Laboratory of Automobile Materials, MOE, and State Key Laboratory of Superhard Materials, Jilin University (China)
2. College of Science, Changchun University, Changchun 130022 (China)
3. State Key Laboratory of Superhard Materials, Jilin University (China)

NbN/W{sub 2}N nano-multilayer films with a modulation periodicity, {Lambda}, ranging from 5.1 to 157.4 nm have been deposited on a Si(100) substrate by reactive magnetron sputtering in Ar/N{sub 2} mixtures. The {Lambda} dependent structural and mechanical properties for the resulting NbN/W{sub 2}N multilayers have been evaluated by means of low-angle x-ray reflectivity, x-ray diffraction, high-resolution transmission electron microscope, and nanoindentation measurements. The finding is that for films with {Lambda}{<=} 10.6 nm, fcc NbN layers are coherent with cubic W{sub 2}N layers, resulting in NbN layers and W{sub 2}N layers that are in the compressive and tensile states, respectively. In contrast, as {Lambda} is larger than 10.6 nm, a phase transition from W{sub 2}N to W occurs in the W{sub 2}N layer, which is a result of the coherent interface strain relaxation. For this case, all layers are in the compressive state, and the coherent interface disappears. The intrinsic compressive stress evolution with {Lambda} can be interpreted in terms of interface stress. The formation of coherent interface at small {Lambda} ({<=}10.6 nm) is helpful for releasing point defects in layers, leading to a low compressive stress ({<=}1.1 GPa). The hardness for the obtained multilayer film increases with decreasing {Lambda}, and approaches a maximum value of 43.7 GPa when {Lambda} is 7.4 nm. The maximum strengthen at lower {Lambda} is mainly attributed to coherent interface stresses and the modulus difference between the NbN and W{sub 2}N layers. The increase in hardness with a decrease in {Lambda} is interpreted by the Lehoczky model.

• OSTI ID: 21538443
• Journal Information: Journal of Applied Physics, Vol. 109, Issue 12; Other Information: DOI: 10.1063/1.3598083; (c) 2011 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
77 NANOSCIENCE AND NANOTECHNOLOGY
COMPRESSION STRENGTH
FCC LATTICES
HARDNESS
LAYERS
NANOSTRUCTURES
NIOBIUM NITRIDES
PHASE TRANSFORMATIONS
POINT DEFECTS
PRESSURE RANGE GIGA PA
REFLECTION
REFLECTIVITY
RELAXATION
SPUTTERING
STRESSES
SUBSTRATES
TENSILE PROPERTIES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN NITRIDES
X-RAY DIFFRACTION
COHERENT SCATTERING
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DIFFRACTION
ELECTRON MICROSCOPY
FILMS
MECHANICAL PROPERTIES
MICROSCOPY
NIOBIUM COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PNICTIDES
PRESSURE RANGE
REFRACTORY METAL COMPOUNDS
SCATTERING
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS