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Optimization of the superconducting properties of NbTiN thin films by variation of the N 2 partial pressure during sputter deposition
We report the effect of nitrogen partial pressure on the growth of niobium-titanium nitride (NbTiN) thin films through reactive sputtering of the NbTi target in the presence of Ar and N 2 atmosphere. The N 2 partial pressure was varied from 5.8% to 15.15% with respect to the Ar flow available in the...
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| Published in: | Superconductor science & technology 2023-08, Vol.36 (8), p.85017 |
|---|---|
| Main Authors: | , , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | We report the effect of nitrogen partial pressure on the growth of niobium-titanium nitride (NbTiN) thin films through reactive sputtering of the NbTi target in the presence of Ar and N
2
atmosphere. The N
2
partial pressure was varied from 5.8% to 15.15% with respect to the Ar flow available in the chamber. We measured a critical temperature (
T
C
) as high as 15.77 K for an N
2
partial pressure of 6.8% for a 50 nm film deposited on an MgO substrate. The epitaxial growth of the NbTiN films is evident from the observed (200) and (400) XRD peaks with respect to the substrate. The superconducting properties were analyzed with respect to the observed values of
T
C,
Δ
T
C,
temperature dependence of the upper critical field (
B
C2
), coherence length (
ξ
), diffusion coefficient (
D
), and the thermally activated flux flow behavior following the Arrhenius equation. The
T
C
variation observed for the entire spectrum of N
2
partial pressure variation is ∼11%, with
T
C
getting saturated towards the higher end of the N
2
content. While the
T
C
variation with respect to N
2
content is non-linear, the variation of
B
C2
(0), diffusion coefficient, and zero temperature coherence length
ξ
(0) show a linear dependence. While the
B
C2
(0) values show an increasing trend,
D
and
ξ
(0) values show a decreasing trend with respect to the increase of N
2
partial pressure. It is concluded that the optimum window of N
2
partial pressure for the reactive sputtering of NbTiN using a target of Nb
0.7
Ti
0.3
for the present experimental conditions, in terms of epitaxial growth and obtaining the highest
T
C
is within the
range of 5.8% to 8.51%. |
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| ISSN: | 0953-2048 1361-6668 |
| DOI: | 10.1088/1361-6668/ace3fa |