Epitaxial and polycrystalline Hf Nx (0.8≤x≤1.5) layers on MgO(001)

Film growth and physical properties

H. S. Seo, Taeyoon Lee, I. Petrov, J. E. Greene, D. Gall

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

While many transition metal (TM) nitrides-including TiN, ZrN, and TaN-have been widely studied and are currently used as hard wear-resistant coatings, diffusion barriers, and optical coatings, little is known about a related TM nitride, HfN. Here, we report the results of a systematic investigation of the growth and physical properties of Hf Nx layers, with 0.80≤x≤1.50, deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering at 650°C in mixed N2 Ar discharges. Hf Nx layers with 0.80≤x≤1.20 crystallize in the B1-NaCl structure with a cube-on-cube epitaxial relationship to the MgO(001) substrate, while films with 1.24≤x≤1.50 contain a N-rich second phase. The relaxed bulk lattice parameter of Hf Nx (001) decreases only slightly with increasing NHf ratio, ranging from 0.4543 nm with x=0.80 to 0.4517 nm with x=1.20. The room-temperature resistivity ρ of stoichiometric HfN(001) is 14.2 μΩ cm and ρ (x) increases with both increasing and decreasing x to 140 μΩ cm with x=0.80 and 26.4 μΩ cm with x=1.20. The hardness H and elastic modulus E of HfN(001) are 25.2 and 450 GPa, respectively. H (x) initially increases for both over- and understoichiometric layers due to defect-induced hardening, while E (x) remains essentially constant. Single-phase Hf Nx (001) is metallic with a positive temperature coefficient of resistivity (TCR) between 50 and 300 K and a temperature- independent carrier density. It is also superconducting with the highest critical temperature, 9.18 K, obtained for layers with x=1.00. In the two phase regime, ρ ranges from 59.8 μΩ cm with x=1.24 to 2710 μΩ cm with x=1.50. TCR becomes positive with x≤1.38, no superconducting transition is observed, and both H and E decrease.

Original languageEnglish
Article number083521
JournalJournal of Applied Physics
Volume97
Issue number8
DOIs
Publication statusPublished - 2005 Apr 27

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physical properties
metal nitrides
electrical resistivity
transition metals
optical coatings
coefficients
hardening
ultrahigh vacuum
temperature
lattice parameters
modulus of elasticity
critical temperature
magnetron sputtering
hardness
coatings
defects
room temperature

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

@article{9663432e553f4cea92201e698844ea78,
title = "Epitaxial and polycrystalline Hf Nx (0.8≤x≤1.5) layers on MgO(001): Film growth and physical properties",
abstract = "While many transition metal (TM) nitrides-including TiN, ZrN, and TaN-have been widely studied and are currently used as hard wear-resistant coatings, diffusion barriers, and optical coatings, little is known about a related TM nitride, HfN. Here, we report the results of a systematic investigation of the growth and physical properties of Hf Nx layers, with 0.80≤x≤1.50, deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering at 650°C in mixed N2 Ar discharges. Hf Nx layers with 0.80≤x≤1.20 crystallize in the B1-NaCl structure with a cube-on-cube epitaxial relationship to the MgO(001) substrate, while films with 1.24≤x≤1.50 contain a N-rich second phase. The relaxed bulk lattice parameter of Hf Nx (001) decreases only slightly with increasing NHf ratio, ranging from 0.4543 nm with x=0.80 to 0.4517 nm with x=1.20. The room-temperature resistivity ρ of stoichiometric HfN(001) is 14.2 μΩ cm and ρ (x) increases with both increasing and decreasing x to 140 μΩ cm with x=0.80 and 26.4 μΩ cm with x=1.20. The hardness H and elastic modulus E of HfN(001) are 25.2 and 450 GPa, respectively. H (x) initially increases for both over- and understoichiometric layers due to defect-induced hardening, while E (x) remains essentially constant. Single-phase Hf Nx (001) is metallic with a positive temperature coefficient of resistivity (TCR) between 50 and 300 K and a temperature- independent carrier density. It is also superconducting with the highest critical temperature, 9.18 K, obtained for layers with x=1.00. In the two phase regime, ρ ranges from 59.8 μΩ cm with x=1.24 to 2710 μΩ cm with x=1.50. TCR becomes positive with x≤1.38, no superconducting transition is observed, and both H and E decrease.",
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Epitaxial and polycrystalline Hf Nx (0.8≤x≤1.5) layers on MgO(001) : Film growth and physical properties. / Seo, H. S.; Lee, Taeyoon; Petrov, I.; Greene, J. E.; Gall, D.

In: Journal of Applied Physics, Vol. 97, No. 8, 083521, 27.04.2005.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Epitaxial and polycrystalline Hf Nx (0.8≤x≤1.5) layers on MgO(001)

T2 - Film growth and physical properties

AU - Seo, H. S.

AU - Lee, Taeyoon

AU - Petrov, I.

AU - Greene, J. E.

AU - Gall, D.

PY - 2005/4/27

Y1 - 2005/4/27

N2 - While many transition metal (TM) nitrides-including TiN, ZrN, and TaN-have been widely studied and are currently used as hard wear-resistant coatings, diffusion barriers, and optical coatings, little is known about a related TM nitride, HfN. Here, we report the results of a systematic investigation of the growth and physical properties of Hf Nx layers, with 0.80≤x≤1.50, deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering at 650°C in mixed N2 Ar discharges. Hf Nx layers with 0.80≤x≤1.20 crystallize in the B1-NaCl structure with a cube-on-cube epitaxial relationship to the MgO(001) substrate, while films with 1.24≤x≤1.50 contain a N-rich second phase. The relaxed bulk lattice parameter of Hf Nx (001) decreases only slightly with increasing NHf ratio, ranging from 0.4543 nm with x=0.80 to 0.4517 nm with x=1.20. The room-temperature resistivity ρ of stoichiometric HfN(001) is 14.2 μΩ cm and ρ (x) increases with both increasing and decreasing x to 140 μΩ cm with x=0.80 and 26.4 μΩ cm with x=1.20. The hardness H and elastic modulus E of HfN(001) are 25.2 and 450 GPa, respectively. H (x) initially increases for both over- and understoichiometric layers due to defect-induced hardening, while E (x) remains essentially constant. Single-phase Hf Nx (001) is metallic with a positive temperature coefficient of resistivity (TCR) between 50 and 300 K and a temperature- independent carrier density. It is also superconducting with the highest critical temperature, 9.18 K, obtained for layers with x=1.00. In the two phase regime, ρ ranges from 59.8 μΩ cm with x=1.24 to 2710 μΩ cm with x=1.50. TCR becomes positive with x≤1.38, no superconducting transition is observed, and both H and E decrease.

AB - While many transition metal (TM) nitrides-including TiN, ZrN, and TaN-have been widely studied and are currently used as hard wear-resistant coatings, diffusion barriers, and optical coatings, little is known about a related TM nitride, HfN. Here, we report the results of a systematic investigation of the growth and physical properties of Hf Nx layers, with 0.80≤x≤1.50, deposited on MgO(001) by ultrahigh vacuum reactive magnetron sputtering at 650°C in mixed N2 Ar discharges. Hf Nx layers with 0.80≤x≤1.20 crystallize in the B1-NaCl structure with a cube-on-cube epitaxial relationship to the MgO(001) substrate, while films with 1.24≤x≤1.50 contain a N-rich second phase. The relaxed bulk lattice parameter of Hf Nx (001) decreases only slightly with increasing NHf ratio, ranging from 0.4543 nm with x=0.80 to 0.4517 nm with x=1.20. The room-temperature resistivity ρ of stoichiometric HfN(001) is 14.2 μΩ cm and ρ (x) increases with both increasing and decreasing x to 140 μΩ cm with x=0.80 and 26.4 μΩ cm with x=1.20. The hardness H and elastic modulus E of HfN(001) are 25.2 and 450 GPa, respectively. H (x) initially increases for both over- and understoichiometric layers due to defect-induced hardening, while E (x) remains essentially constant. Single-phase Hf Nx (001) is metallic with a positive temperature coefficient of resistivity (TCR) between 50 and 300 K and a temperature- independent carrier density. It is also superconducting with the highest critical temperature, 9.18 K, obtained for layers with x=1.00. In the two phase regime, ρ ranges from 59.8 μΩ cm with x=1.24 to 2710 μΩ cm with x=1.50. TCR becomes positive with x≤1.38, no superconducting transition is observed, and both H and E decrease.

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