FP-LAPW investigation of electronic structure of TaN and TaC compounds

Sahnoun, M.; Daul, Claude; Driz, M.; Parlebas, J.C.; Demangeat, C.

doi:10.1016/j.commatsci.2004.12.010

Cited by 76 publications

(46 citation statements)

References 42 publications

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“…Generally, the error in elasticity calculations based on the DFT is order of 10%, resulted mainly from the exchange-correlation approximation and the pseudopotential employed in the calculations. From Table I, our results are in reasonable agreement with those obtained by the projector augmented-wave (PAW) method, 26,28 the DFT method, 25 the FLAPW plus local orbitals (FLAPW þ lo) method, 16 the relativistic Korringa, Kohn, and Rostoker (KKR) method, 14 and the density functional perturbation theory (DFPT) method. 17 Thus, consider the typical error, the good agreement between current and previous results, supporting the accuracy and reliability of our elastic calculations.…”

Section: B Elastic Propertiessupporting

confidence: 78%

“…13 These wide ranges of interesting applications have lead to much efforts that have been devoted to this fascinating material. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In the past, a number of studies mainly focus on cubic d phase of TaN by the various methods [14][15][16][17][18][19] and also synthesized by diverse methods, [20][21][22] calculations show very high bulk modulus (above 328 GPa) and suggest that TaN is in cubic d phase with high hardness. Compared to the cubic phase, the e and h phases have not been studied deeply.…”

Section: Introductionmentioning

confidence: 99%

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Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

Chang

Zhao

Zhou

et al. 2012

Journal of Applied Physics

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The structure and mechanical properties of tantalum mononitride (TaN) are investigated at high pressure from first-principles using the plane wave pseudopotential method within the local density approximation. Three stable phases were considered, i.e., two hexagonal phases (e and h) and a cubic d phase. The obtained equilibrium structure parameters and ground state mechanical properties are in excellent agreement with the experimental and other theoretical results. A full elastic tensor and crystal anisotropy of the ultra-incompressible TaN in three stable phases are determined in the wide pressure range. Results indicated that the elastic properties of TaN in three phases are strongly pressure dependent. And the hexagonal h-TaN is the most ultraincompressible among the consider phases, which suggests that the h phase of TaN is a potential candidate structure to be one of the ultraincompressible and hard materials. By the elastic stability criteria, it is predicted that h-TaN is not stable above 53.9 GPa. In addition, the calculated B/G ratio indicated that the e and d phases possess brittle nature in the range of pressure from 0 to 100 GPa. While h phase is brittleness at low pressure (below 8.2 GPa) and is strongly prone to ductility at high pressure (above 8.2 GPa). The calculated elastic anisotropic factors for three phases of TaN suggest that they are elastically highly anisotropic and strongly dependent on the propagation direction.

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Section: B Elastic Propertiessupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

Chang

Zhao

Zhou

et al. 2012

Journal of Applied Physics

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“…Based on these experimental facts, theoretical calculations were performed to investigate electronic structures and elastic properties because these material are expected to be hard materials. [6][7][8][9][10][11][12] In this study, we focus on nitride compounds and their magnetic properties, which is different from the above works. It is well known that nitrides prefer ferromagnetic ͑FM͒ states.…”

Section: Introductionmentioning

confidence: 99%

Synthetic ferromagnetic nitrides: First-principles calculations of CaN and SrN

et al. 2007

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Encouraged by recent experimental facts of synthesizing materials which do not exist in nature, we introduce a type of ferromagnets, CaN and SrN, which have been proposed by first-principles calculations. These are half-metallic ferromagnets and they have magnetic moments of 1 B per chemical formula unit. Out of typical structures of binary compounds we have calculated, the rocksalt structure is the most stable form for both CaN and SrN. The majority of the magnetic moment of these compounds originates from the nitrogen sites since the p states of nitrogen are spin polarized. The mechanism of the ferromagnetism is discussed. Their formation energies have been calculated and the results show that it should be feasible to synthesize these materials. The structural stability of CaN has been confirmed by performing first-principles molecular dynamics simulations. We propose a synthesis process for CaN using the high pressure and temperature environment.

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“…However the relationship between the barrier efficiency and material structure has not been established. On the theoretical side, research has focused on bulk properties 15 and electronic structures of TaN compounds, [16][17][18] the thermal stability of Cu/TaN/Si stacking structures, 19 and statistical modeling of atomic diffusions. 20 However, the crucial issues such as why and how TaN compounds work as diffusion barrier materials are still not well understood.…”

Section: Introductionmentioning

confidence: 99%

First-principles simulations of copper diffusion in tantalum and tantalum nitride

Zhao

Lü

2009

Phys. Rev. B

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To explore potential applications of tantalum and tantalum nitrides ͑TaN͒ as diffusion barrier materials in integrated circuits with Cu interconnects, we carry out detailed first-principles simulations of Cu/Ta and Cu/TaN systems. Various interfacial structures between Cu-and Ta-based compounds are examined by considering different surface orientations, in-plane arrangements, surface terminations, and chemical compositions. The coexistence of strong Cu-N ionic bonding and Ta-Cu covalent/metallic bonding dictates the stable interfacial structures. Using nudged elastic band method, we calculate the diffusion energy barriers of Cu to the pre-existing vacancies across Cu/Ta, Cu/TaN interfaces, and in bulk TaN compounds. As a comparison, Cu diffusion in Si is also studied. It was found that Cu can easily diffuse into Si either spontaneously or with small energy barriers. On the other hand, although the Cu/Ta interfacial diffusion barrier is low, the high vacancy formation energy in Ta renders Cu diffusion difficult. We find that fcc TaN is an excellent candidate for diffusion barrier material owing to its extremely high interfacial diffusion energy barrier. The bulk diffusion barrier of Cu in fcc TaN is also very high.

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FP-LAPW investigation of electronic structure of TaN and TaC compounds

Cited by 76 publications

References 42 publications

Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

Structure and mechanical properties of tantalum mononitride under high pressure: A first-principles study

Synthetic ferromagnetic nitrides: First-principles calculations of CaN and SrN

First-principles simulations of copper diffusion in tantalum and tantalum nitride

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