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Article

КВАНТОВЫЕ РАЗМЕРНЫЕ ЭФФЕКТЫ В МЕТАЛЛИЧЕСКИХ НАНОСТРУКТУРАХ

Доклады Академии Наук. Физика. 2015. Т. 3. № 28. С. 7-16.

Quantum size phenomena develop when the dimension(s) of a system approach certain characteristic
scales. Modern nanotechnology enables routine and reproducible fabrication of
nanostructures with sub-100 nm features where such effects might be pronounced. In this research
we used lift-off lithography and vacuum metal deposition to fabricate bismuth (semimetal) and titanium (superconductor) nanowires. Then low energy argon ion beam etching was used to progressively
reduce the cross section of the structures. Electron transport properties were measured
at low temperatures between the sessions of etching. Oscillations of electric resistance and its
pronounced increase below ~70 nm scales were observed when bismuth nanowire cross section
was reduced. The observation can be interpreted as a manifestation of electron spectra size quantization
in narrow semimetal channels. We observed broadening of the resistive transition in
superconductors with reduction of the nanowire cross section. In the thinnest samples finite resistance
was observed even at temperatures much lower than the bulk critical temperature. The
phenomenon can be understood as manifestation of the quantum phase slip effect specific for
ultra narrow superconducting channels. Both quantum size effects (in semimetals and superconductors)
are in good agreement with the existing models. The existence of quantum size phenomena
in metallic systems imposes fundamental limitations on the utilization of such ultra-small
components in nanoelectronic circuits.