Abstract
Anodizing of Ta-Al metal bilayers (Al on Ta) sputter-deposited onto SiO2 substrates was performed in oxalic acid electrolytes at anode potentials of 53 to 21.5 V in order to form nanoporous alumina layers and sequentially oxidize the tantalum underlayers through the alumina pores. The films formed consist of arrays of tantalum oxide nanohillocks percolating through the residual tantalum layer down to the substrate, so that a self-organized network of tantalum nanowires forms between the substrate and the alumina film. The average width (25–<10 nm), length (70–35 nm), and population density (109–1011 cm-2) of the nanowires are systematically defined by the initial tantalum thickness (8–22 nm) and the anodizing conditions. The mesh-like, nano-sized morphologies of the tantalum underlayers result in a remarkably wide range of potential-dependent, controlled electrical sheet resistances (102–107 Ω/sq). The periodical, tunable, metal/insulator film structure, allowing an increased transition to hopping or tunneling conduction at elevated temperature, leads to negative temperature coefficients of resistance, ranging 300 to 5 ppm/K. Oscillations of the potential-dependent dc conductance registered in the films at room temperature are attributed to the quantum-size effects in the metal/oxide nanostructures. The films are of technological importance for fabrication of thin-film, planar, adjustable resistors with significantly improved performances.
Similar content being viewed by others
References
B. BHUSHAN (Ed.), “Springer Handbook of Nanotechnology” (Spinger-Verlag, Berlin, Heidelberg, New York, 2003).
A. MOZALEV, M. SAKAIRI and H. TAKAHASHI, J. Electrochem. Soc. 151 (2004) F257–F268.
A. MOZALEV, M. SAKAIRI, I. SAEKI and H. TAKAHASHI, Electrochim. Acta 48 (2003) 3155.
A. MOZALEV, A. SURGANOV and S. MAGAINO, ibid. 44 (1999) 3891.
G. C. SCHWARTZ and V. PLATTER, J. Electrochem. Soc. 122 (1975) 1508.
Idem., ibid. 123 (1976) 34.
V. SURGANOV and A. MOZALEV, Microelectron. Eng. 37/38 (1997) 329.
S. LAZAROUK, S. KATSOUBA, A. LESHOK, A. DEMIANOVICH, V. STANOVSKI, S. VOITECH, V. VYSOTSKI and V. PONOMAR, ibid. 50 (2000) 321.
I. VRUBLEVSKY, V. PARKOUN, V. SOKOL and J. SCHRECKENBACH, Appl. Sur. Sci. 236 (2004) 270.
G. C. WOOD, in “Oxides and Oxide Films”, edited by J. W. Diggle (Marcell Dekker, New York, 1987) Vol. 2, p. 41.
R. C. FURNEAUX G. E. THOMPSON and G. C. WOOD, Corros. Sci. 18 (1978) 853.
M. NAGAYAMA, H. TAKAHASHI and K. FUJIMOTO, in “Application of Complex Plane Analysis to Electrochemistry”, (USA Office of The Electrochemical Society of Japan, Cleveland, OH 1982) p. 1.
A. LLOYD SPETZ, D. SCHMEIBER, A. BARANZAHI, B. WALIVAARA, W. GOPEL and I. LUNDSTROM, Thin Solid Films 299 (1997) 183.
A. MOZALEV, Ph.D. thesis, Belarusian State University of Informatics and Radio-electronics, Minsk, 1992.
H. HABAZAKI, P. SKELDON, G. E. THOMPSON and G. C. WOOD, Phil. Mag. B71 (1995) 81.
J. DE LAET, H. TERRYN and J. VEREECKEN, Electrochimica Acta 41 (1995) 1155.
F. J. HIMPSEL, J. E. ORTEGA, G. J. MANKEY and R. F. WILLIS, Adv. Phys. 47 (1998) 511.
L. MAISSEL and R. GLANG, “Handbook of Thin Film Technology” (McGraw-Hill, New York, 1970) Vol. 2.
M. MILUN, Croatica Chemica Acta 74(4) (2001) 887.
K. CHU, J. P. CHANG, M. L. STEIGERWALD, R. M. FLEMING, R. L. OPILA, D. V. LANG, R. B. VAN DOVER and C. D. W. JONES, J. Appl. Phys. 91 (2002) 308.
E. I. ROGACHEVA, T. V. TAVRINA, O. N. NASHCHEKINA, S. N. GRIGOROV, K. A. NASEDKIN, M. S. DRESSELHAUS and S. B. CRONIN, Appl. Phys. Lett. 15 (2002) 2690.
D. A. WHARAM, T. J. THORNTON, R. NEWBURY, M. PEPPER, H. AHMED, J. E. F. FROST, D. G. HASKO, D. C. PEACOCK, D. A. RITCHIE and G. A. C. JONES, J. Phys. C: Solid State Phys. 21 (1988) L209.
C. J. MULLER, J. M. KRANS, T. N. TODOROV and M. A. REED, Phys. Rev. B 53 (1996) 1022.
M. JALOCHOWSKI, E. BAUER, H. KNOPPE and G. LILIENKAMP, ibid. 45 (1992) 13607.
A. MOZALEV, M. SAKAIRI and H. TAKAHASHI, in Proceedings of the 18th National Conference of Japan's Anodizing Research Society (ARS), 2001, Osaka, Japan, p. 55.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Mozalev, A., Gorokh, G., Sakairi, M. et al. The growth and electrical transport properties of self-organized metal/oxide nanostructures formed by anodizing Ta-Al thin-film bilayers. J Mater Sci 40, 6399–6407 (2005). https://doi.org/10.1007/s10853-005-1620-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10853-005-1620-9