Abstract
Chemical composition of very thin niobium oxide layers grown on the surface of 200-nm niobium films was determined by X-ray photoelectron spectroscopy (XPS or ESCA). The oxides were fabricated by rf plasma oxidation under conditions that minimize the incorporation of impurities such as carbon in the Nb2O5 Josephson junction tunnel barriers. Nb 3d XPS core level peak positions, areas, and area ratios were used to determine the presence of different oxidation states of Nb, their relative abundance, and surface oxide thickness. The observed composition deviated from what is usually assumed for an ideal model superconductor-insulator structure. The oxide was incompletely oxidized Nb2O5-δ with δ decreasing from 0.2 to 0.1 with increasing oxide thickness from 2 to 4 nm. A 0.5-nm interface region was observed between the metal and oxide.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
L. Solymar,Superconductive Tunnelling and Applications (Wiley-Interscience, New York, 1972), p. 43.
M. D. Sherill and H. H. Edwards,Phys. Rev. Lett. 6, 460 (1961).
P. Townsend and J. Sutton,Phys. Rev. 128, 591 (1962).
M. L. A. MacVicar and R. M. Rose,Phys. Lett. 26A, 510 (1968).
J. E. Nordman,J. Appl. Phys. 40, 2111 (1969).
R. B. Laibowitz and J. J. Cuomo,J. Appl. Phys. 41, 2748 (1970).
K. Schwidtal,J. Appl. Phys. 43, 202 (1972).
G. Hawkins and J. Clarke,J. Appl. Phys. 47, 1616 (1976).
R. F. Broom,J. Appl. Phys. 47, 5432 (1976).
W. H. Keller and J. E. Nordman,J. Appl. Phys. 44, 4732 (1973).
B. Robinson, T. H. Geballe, and J. M. Rowell, inSuperconductivity in d-and f- Band Metals, D. H. Douglass, ed. (Plenum Press, New York, 1976).
S. J. Bean and D. Chadwick, inProceedings of the Fourth International Conf. on Solid Surfaces and Third European Conference on Surface Science, D. A. Degras and M. Costa, ed. (F. Berger and Söhne, Vienna, 1977), Vol. I, p. 551.
M. Grundner and J. Halbritter,J. Appl. Phys. 51, 397 (1980).
P. C. Karulkar and J. E. Nordman,Applications Surf. Sci. 4, 282 (1980).
R. F. Marks, R. A. Pollak, Ph. Avouris, C. T. Lin, and Y. J. Théfaine,J. Chem. Phys. 78, 4270 (1983).
S. I. Raider and R. E. Drake,IEEE Trans. Magn. MAG-17, 299 (1981).
S. I. Raider, R. W. Johnson, T. S. Kuan, R. E. Drake, and R. A. Pollak,IEEE Trans. Magn. MAG-19, 803 (1983).
M. Grundner,Proceedings of the 7th International Vacuum Congress & 3rd International Conference on Solid Surfaces (F. Berger and Söhne, Vienna, 1977), p. 2237.
C. S. Fadley, R. J. Baird, W. Siekhaus, T. Novakov, and S. Å. L. Bergstrom,J. Electron Spectrosc. Relat. Phenom. 6, 94 (1972).
B. M. Gatehouse and A. D. Wadsley,Acta Crystallogr. 17, 1545 (1964).
J. H. Greiner,J. Appl. Phys. 42, 5151 (1971).
P. C. Karulkar,J. Vac. Sci. Technol. 42, 169 (1981).
M. Grundner and J. Halbritter,J. Appl. Phys. 51, 5396 (1980).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pollak, R.A., Stolz, H.J., Raider, S.I. et al. Chemical composition and interface chemistry of very thin Nb2O5 films prepared by rf plasma oxidation. Oxid Met 20, 185–192 (1983). https://doi.org/10.1007/BF00656840
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00656840