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Dependence of superconductivity on the crystallinity of Nb films on Si wafers

  • Received : 2021.12.18
  • Accepted : 2021.12.30
  • Published : 2021.12.31

Abstract

Among elemental metals, niobium (Nb) has the highest superconducting transition temperature (Tc) at ambient pressure. Thus, Nb films have been used in superconducting electronics and radio frequency cavity applications. In this study, the depositional factors determining the crystallinity and Tc of Nb films were investigated. An Nb film grown at a sputtering temperature of 240℃ exhibited the maximum crystallinity of Nb and the minimum crystallinity of niobium oxide. X-ray photoelectron spectroscopy confirmed a maximum atomic percent of niobium and a minimum atomic percent of oxygen. A sputtering power of 210 W and a sputtering time of 50 min were the optimal conditions for Nb deposition, and the Tc of the optimized film (9.08 K) was close to that of bulk Nb (9.25 K). Transmission electron microscopy images of the thick film directly confirmed the removal of the typical in-plane compressive strain in the (110) plane caused by residual stress.

Keywords

Acknowledgement

This work was funded by the National Research Foundation of Korea (NRF), Nos. NRF-2019R1A2C1089017 and NRF-2019R1I1A1A01061738; and the Ministry of SMEs and Startups (MSS, Korea), No. S2912700.

References

  1. M. Peiniger and H. Piel, "A superconducting Nb3Sn coated multicell accelerating cavity," IEEE Transactions on Nuclear Science, vol. NS-32, no. 5, p. 3610, 1985. https://doi.org/10.1109/TNS.1985.4334443
  2. D. K. Finnemore, T. F. Stromberg, and C. A. Swenson, "Superconducting Properties of High-Purity Niobium," Physical Review, vol. 149, no. 1, p. 231, 1966, doi: 10.1103/PhysRev.149.231.
  3. L. N. Hand, J. P. Craig, and W. R. Frisken, "Characterization of Niobium films and a bulk Niobium sample with RRR, SIMS and a SQUID Magnetometer," Proceedings of the 11th Workshop on RF Superconductivity (SRF' 03), Lubeck, Germany, Sep. 2003 paper THP07, p. 604, 2003.
  4. M. Delheusy et al., "X-ray investigation of subsurface interstitial oxygen at Nb/oxide interfaces," Applied Physics Letters, vol. 92, no. 10, p. 101911, 2008, doi: 10.1063/1.2889474.
  5. M. Frommberger et al., "Properties of Nb thin films and their application for diffusion cooled Hot-Electron Bolometer," Proceedings of the 11th International Symposium on Space Terahertz Technology, edited by A. Ann(University of Michigan, MI USA, 2000), p. 489, 2000.
  6. C. Delacour et al., "Persistence of superconductivity in niobium ultrathin films grown on R-plane sapphire," Physical Review B, vol. 83, no. 14, p. 144504, 2011, doi: 10.1103/PhysRevB.83.144504.
  7. W. M. Roach et al., "Niobium thin film deposition studies on copper surfaces for superconducting radio frequency cavity applications," Physical Review Special Topics - Accelerators and Beams, vol. 15, no. 6, p. 062002, 2012, doi: 10.1103/PhysRevSTAB.15.062002.
  8. M. Trezza et al., "Superconducting properties of Nb thin films deposited on porous silicon templates," Journal of Applied Physics, vol. 104, no. 8, p. 083917, 2008, doi: 10.1063/1.3006014.
  9. E. Valderrama et al., "Nb film growth on crystalline and amorphous subsrates," Proceedings of 15th International Conference on RF Superconductivity, Chichgo, USA, p. 898, 2011.
  10. N. N. Iosad, T. M. Klapwijk, S. N. Polyakov, V. V. Roddatis, E. K. Kov'ev, and P. N. Dmitriev, "Properties of DC magnetron sputtered Nb and NbN films for different source conditions," IEEE Transactions on Applied Superconductivity, vol. 9, no. 2, p. 1720, 1999. https://doi.org/10.1109/77.784785
  11. G. i. Oya, M. Koishi, and Y. Sawada, "High-quality single-crystal Nb films and influences of substrates on the epitaxial growth," Journal of Applied Physics, vol. 60, no. 4, p. 1440, 1986, doi: 10.1063/1.337323.
  12. J. Choi et al., "Analysis of the Superconducting Characteristics of Niobium Thin Films Deposited by Using a DC Magnetron Sputtering System," New Physics: Sae Mulli, vol. 68, no. 3, p. 284, 2018, doi: 10.3938/npsm.68.284.
  13. J. Choi, Y.-K. Kim, C.-D. Kim, S. Kim, and Y. Jo, "Enhancing the critical temperature of strained Niobium films," Materials Research Express, vol. 7, no. 7, p. 076001, 2020, doi: 10.1088/2053-1591/aba84a.
  14. L. R. Nivedita, A. Haubert, A. K. Battu, and C. V. Ramana, "Correlation between Crystal Structure, Surface/Interface Microstructure, and Electrical Properties of Nanocrystalline Niobium Thin Films," Nanomaterials, vol. 10, no. 7, Jun 30 2020, doi: 10.3390/nano10071287.
  15. J. A. Thornton, "Influence of apparatus geometry and deposition conditions on the structure and topography of thick sputtered coatings," Journal of Vacuum Science and Technology, vol. 11, no. 4, pp. 666-670, 1974, doi: 10.1116/1.1312732.
  16. A. Anders, "A structure zone diagram including plasma-based deposition and ion etching," Thin Solid Films, vol. 518, no. 15, pp. 4087-4090, 2010, doi: 10.1016/j.tsf.2009.10.145.
  17. M. Maniruzzaman and A. Noya, "Interpretation of Cu(111)//Nb(110) growth on SiO2 by transmission electron microscopy," 5th International Conference on Electrical and Computer Engineering ICECE 2008, 20-22 December 2008, Dhaka, Bangladesh, p. 812, 2008.
  18. E. Pehlivan and G. A. Niklasson, "Fractal dimensions of niobium oxide films probed by protons and lithium ions," Journal of Applied Physics, vol. 100, no. 5, p. 053506, 2006, doi: 10.1063/1.2337164.
  19. S. J. Rezvani et al., "Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms," Condensed Matter, vol. 4, no. 1, 2019, doi: 10.3390/condmat4010004.
  20. S. Venkataraj, R. Drese, C. Liesch, O. Kappertz, R. Jayavel, and M. Wuttig, "Temperature stability of sputtered niobium-oxide films," Journal of Applied Physics, vol. 91, no. 8, pp. 4863-4871, 2002, doi: 10.1063/1.1458052.
  21. J. Halbritter, "Transport in superconducting niobium films for radio frequency applications," Journal of Applied Physics, vol. 97, no. 8, 2005, doi: 10.1063/1.1874292.
  22. O. V. Dobrovolskiy and M. Huth, "Crossover from dirty to clean superconducting limit in dc magnetron-sputtered thin Nb films," Thin Solid Films, vol. 520, no. 18, p. 5985, 2012, doi: 10.1016/j.tsf.2012.04.083.
  23. T. J. Hwang and D. H. Kim, "Transition temperatures and upper critical fields of NbN thin films fabricated at room temperature," Progress in Superconductivity and Cryogenics, vol. 17, no. 3, p. 9, 2015, doi: 10.9714/psac.2015.17.3.009.
  24. K. Choi, H. Choi, H. Na, and I. Sohn, "Effect of magnesium on the phase equilibria in magnesio-thermic reduction of Nb2O5," Materials Letters, vol. 183, p. 151, 2016, doi: 10.1016/j.matlet.2016.07.058.
  25. M. Jha, K. V. Ramanujachary, S. E. Lofland, G. Gupta, and A. K. Ganguli, "Novel borothermal process for the synthesis of nanocrystalline oxides and borides of niobium," Dalton Transactions, vol. 40, no. 31, p. 7879, Aug 21 2011, doi: 10.1039/c1dt10468c.
  26. A. Mozalev et al., "Formation-structure-properties of niobium-oxide nanocolumn arrays via self-organized anodization of sputter-deposited aluminum-on-niobium layers," Journal of Materials Chemistry C, vol. 2, no. 24, p. 4847, 2014, doi: 10.1039/c4tc00349g.
  27. T. Hryniewicz, K. Rokosz, and H. R. Z. Sandim, "SEM/EDX and XPS studies of niobium after electropolishing," Applied Surface Science, vol. 263, p. 357, 2012, doi: 10.1016/j.apsusc.2012.09.060.
  28. K. Zhussupbekov et al., "Oxidation of Nb(110): atomic structure of the NbO layer and its influence on further oxidation," Scientific Reports, vol. 10, no. 1, p. 3794, Mar 2 2020, doi: 10.1038/s41598-020-60508-2.
  29. T. Imamura and S. Hasuo, "Fabrication of high quality Nb/AlOx-Al/Nb Josephson Junctions: II-deposition of thin Al layers on Nb films," IEEE Transactions on Applied Superconductivity, vol. 2, no. 2, p. 84, 1992. https://doi.org/10.1109/77.139224
  30. X. Q. Jia et al., "High Performance Ultra-Thin Niobium Films for Superconducting Hot-Electron Devices," IEEE Transactions on Applied Superconductivity, vol. 23, no. 3, pp. 2300704-2300704, 2013, doi: 10.1109/tasc.2012.2235508.
  31. J. Yu et al., "Hydrothermally formed functional niobium oxide doped tungsten nanorods," Nanotechnology, vol. 24, no. 49, p. 495501, Dec 13 2013, doi: 10.1088/0957-4484/24/49/495501.
  32. C. C. Koch, J. O. Scarbrough, and D. M. Kroeger, "Effects of interstitial oxygen on the superconductivity of niobium," Physical Review B, vol. 9, no. 3, pp. 888-897, 1974, doi: 10.1103/PhysRevB.9.888.
  33. N. M. Jisrawi et al., "Reversible depression in the Tc of thin Nb films due to enhanced hydrogen adsorption," Physical Review B, vol. 58, no. 10, p. 6585, 1998. https://doi.org/10.1103/PhysRevB.58.6585