Effects of substrate bias on the preferred orientation, phase transition and mechanical properties for NbN films grown by direct current reactive magnetron sputtering

Abstract

Articles you may be interested inRelatively low temperature synthesis of hexagonal tungsten carbide films by N doping and its effect on the preferred orientation, phase transition, and mechanical properties NbN films are deposited using direct current reactive magnetron sputtering in discharge of a mixture of N 2 and Ar gas, and the effects of substrate bias ͑V b ͒ on the preferred orientation, phase transition, and mechanical properties for NbN films are explored by x-ray diffraction, selective area electron diffraction, and nanoindentation measurements. It is found that V b has a significant influence on the stress in NbN films, leading to a pronounced change in the preferred orientation, phase structure, and hardness. As the substrate is at voltage floating, the stress is tensile. In contrast, as negative V b is applied, the stress becomes compressive, and increases with increasing the absolute value of negative V b . It is observed that a phase transition from ␦ ͑face-centered cubic͒ to ␦Ј ͑hexagonal͒ for NbN films occurs as V b is in the range of −80 to − 120 V, which can be attributed to a decrease in the strain energy for NbN films. In order to explore the relationship between the stress and phase transition as well as preferred orientation, density-functional theory based on first principles is used to calculate the elastic constants and shear modulus for NbN with a structure of ␦ or ␦Ј. The calculated results show that the shear modulus for ␦Ј-NbN is larger than that for ␦-NbN, whereas the bulk modulus for ␦Ј-NbN is almost equal to that for ␦-NbN, resulting in a difference in hardness for ␦or ␦Ј-NbN single crystal.

Structural and mechanical properties of NbN and Nb-Si-N films: Experiment and molecular dynamics simulations

“…It was shown that the NbN system crystallizes in different structural phases: cubic δ-NbN (a small number of vacancies are present in both the sublattices, space group Fm-3m) and hexagonal ε-NbN (space group P-6 m2) and δ ′-NbN (space group P6 3 /mmc), depending on deposition parameters. The formation of the hexagonal phases occurs at high nitrogen partial pressures and substrate biases [14][15][16]18]. The hardness of the hexagonal δ′ and ε phases of NbN is higher compared to that of the cubic δ-NbN [14,15].…”

“…The hardness of the NbN films deposited by different arc deposition systems reaches 34-49 GPa [8][9][10][11][12][13]. The NbN films were also prepared by using magnetron sputtering (MS) [14][15][16][17][18], ion Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ceramint beam assisted deposition [19], pulsed laser deposition [20]. An increase in hardness was reached by the formation of the nanocomposite or nanolayered structures in ternary Nb-Si-N films [21][22][23][24][25][26][27][28][29].…”

Multilayered vacuum-arc nanocomposite TiN/ZrN coatings before and after annealing: Structure, properties, first-principles calculations

“…A varying the deposition conditions, such as gas pressure in the deposition chamber, bias potential, bilayer thickness, etc. allows to fabricate coatings with very high hardness [9][10][11], good wear coefficient and resistance to wear, oxidation [12][13][14][15][16][17] and to corrosion [18,19] as well as with good electrical properties [20,21]. As it was reported in the previous papers [22,23], coatings on the (Ti,Zr)N base have high hardness 42-48 GPa, as well as resistance to oxidation under the influence of high temperatures 1170°С [24][25][26][27][28].…”

Nanocomposite Nb-Al-N coatings: Experimental and theoretical principles of phase transformations

“…2a). A formation of the preferred orientation (200) caused the reduction of the coating surface energy [70,71]. Figure 3 shows the SEM image of the Nb-Al-N coatings before (а-с) and after annealing (d).…”