ENHANCED MAGNETORESISTIVE EFFECT IN NICKEL NANOPILLAR ARRAYS ON SILICON SUBSTRATES

We show that the magnetoresistive properties of n−Si/SiO2/Ni nanostructures containing nanogranular nickel pillars in verticals pores of the SiO2 layer differ considerably from those properties of previously studied nanogranular Ni films electrodeposited onto n−Si wafers. The electrophysical properties of these nanostructures are similar to those of a system consisting of two opposite−connected Si/Ni Shottky diodes. We studied the magnetoresistance of these structures in the 2—300 K temperature range and in magnetic fields of up to 8 Tl. The studies suggest that at 17—27 K the structures have a posi- tive magnetoresistive effect the magnitude of which depends on the transverse bias applied to the structure and increases with a decrease in the longitudinal current (along the pillars). At 100 nA current, the relative magnetoresistance in a 8 Tl field increased by 500 to 35,000% as the transverse bias varies from 0 to −2 V. The magnetoresistive effect observed in the structures is likely to be related to the effect of the magnetic field on the impact ionization of the impurities causing an avalanche breakdown of the Si/Ni Shottky diode. We prove the possibility of controlling the magnetoresistive effect in n−Si/SiO2/Ni template structures by applying an additional (transverse) electric field to the nanostructure between the silicon substrate (functioning as the third electrode) and the nickel nanopillars.

1. Imry, Y. Nanostructures and mesoscopic systems / Y. Imry. − New York Academic : 1992. − P. 11.

2. Baibich, M. N. Giant Magnetoresistance of (001)Fe/(001)Cr magnetic superlattices / M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, F. Petroff, P. Etienne, G. Creuzet, A. Friederich, J. Chazelas // Phys. Rev. Lett. − 1988. − V. 61. − P. 2472—2475.

3. Garcia, N. Magnetoresistance in excess of 200% in ballistic Ni nanocontacts at room temperature and 100 Oe / N. Garcia, M. Munoz, Y.−W. Zhao // Ibid. − 1999. − V. 82. − P. 2923—2926.

4. Schmidt, G. Spintronics in semiconductor nanostructures / G. Schmidt, C. Gould, L. W. Molenkamp // Physica E. − 2004. − V. 25. − P. 150—159.

5. Template−based synthesis of nanorod or nanowire arrays // Springer Handbook of nanotechnology / Ed. by Bharat Brush- an − Heidelberg; Dordrecht; London; New York : Springer, 2007. − P. 161—178.

6. Nanofunctional materials, nanostructures and novel devices for biological and chemical detection / Ed. by C. Li, A. Zribi, L. Nagahara, M. Willander. − Warrendale (PA), 2007.

7. Magnetic ultrathin films: multilayers and surfaces/interfaces and characterization / Ed. by B. T. Jonker et al. − Warrendale (PA), 1990.

8. Fink, D. Etched ion tracks in silicon oxide and silicon oxyni- tride as charge injection or extraction channels for novel electronic structures / D. Fink, A. V. Petrov, K. Hoppe, W. R. Fahrner, R. M. Pa- paleo, A. S. Berdinsky, A. Chandra, A. Chemseddine, A. Zrineh, A. Biswas, F. Faupel, L. T. Chadderton // Nuclear Instrum. and Meth. in Phys. Res. B. − 2004. − V. 218. − P. 355—361.

9. Streltsov, E . A . Effect of Cd(II) on electrodeposition of textured PbSe / E. A. Streltsov, N. P. Osipovich, L. S. Ivashkevich, A. S. Lyakhov // Electrochim. Acta. − 1999. − V. 44. − P. 2645—2652.

10. Fink, D. Nanotechnology with ion track — tailored media / D. Fink, D. Sinha, J. Opitz− Coutureau, A. V. Petrov, S. E. Demyanov, W. R. Fahrner, K. Hoppe, A. K. Fedotov, L. T. Chadderton, A. S. Berdinsky // Physics, Chemistry and Application of Nanostructures. Mater. of the «Nanomeeting−2005». − Minsk (Belarus), 2005. − P. 474.

11. Ivanova, Yu. A. Electrochemical deposition of Ni and Cu onto monocrystalline n−Si(100) wafers and into nanopores in Si/SiO2 template / Yu. A. Ivanova, D. K. Ivanou, A. K. Fedotov, E. A. Streltsov, S. E. Demyanov, A. V. Petrov, E. Yu. Kaniukov, D. Fink // J. Mater. Sci. − 2007. − V. 42. − P. 9163—9165.

12. Fedotova, J. Magnetoresistance in n−Si/SiO2/Ni nanos-tructures manufactured by swift heavy ion−induced modification technology / J. Fedotova, D. Ivanou, Yu. Ivanova, A. Fedotov, A. Mazanik, I. Svito, E. Streltsov, A. Saad, S. Tyutyunnikov, T. N. Koltunowicz, S. Demyanov, V. Fedotova // Acta Physica Polonica A. − 2011. − V. 120. − P. 133—135.

13. Fedotova, J. Gigantic magnetoresistive effect in n−Si/SiO2/ Ni nanostructures fabricated by the template−assisted electrochemical deposition / J. Fedotova, A. Saad, D. Ivanou, Yu. Ivanova, A. Fedotov, A. Mazanik, I. Svito, E. Streltsov, S. Tyutyunnikov, T. N. Koltunowicz // Electrical Rev. − 2012. − V. 88. − P. 305—308.

14. Delmo, M . P. Large positive magnetoresistive effect in silicon induced by the space − charge effect / M. P. Delmo, Sh. Yamamoto, Sh. Kasai, T. Ono, K. Kobayashi // Nature. − 2009. − V. 457. − P. 1112—1115.

15. Lanyon, H. P. D. Magnetoresistance of silicon diodes reverse biased into breakdown / H. P. D. Lanyon, W. S. Neal // Phys. status solidi (a). − 1974. − V. 21. − P. 605—616.

16. Lanyon, H. P. D. Magnetoresistance of avalanching semiconductor diodes / H. P. D. Lanyon // Ibid. − 1974. − V. 21. − P. 197— 207.

17. Lutsev, L . V. Giant magnetoresistance in semiconduc- tor / granular film heterostructures with cobalt nanoparticles / L. V. Lutsev, A. I. Stognij, N. N. Novitskii // Phys. Rev. B. − 2009. − V. 80. − P. 184423.

18. Fedotova, J. Magnetotransport in nanostructured Ni films electrodeposited on Si substrate / J. Fedotova, A. Saad, D. Ivanou, Yu. Ivanova, A. Fedotov, A. Mazanik, I. Svito, E. Streltsov, S. Tyutyunnikov, T. N. Koltunowicz // Electrical Rev. − 2012. − V. 88. − P. 90—92.