An ion beam based dry etching method has been developed for progressive reduction of dimensions of pre-fabricated nanostructures. The method has been successfully applied to aluminum and bismuth nanowires. We were able to reduce the effective diameter of nanowires from ~ 100 nm down to ~ 8 nm without noticeable degradation of the sample structure. In case of a normal metal (bismuth) we observed a periodic variation of the wire resistance with reduction of its effective diameter. The effect is associated with quantum size phenomenon: crossing of the size-quantized energy levels with the Fermi level. In superconducting nanowires (aluminum) with effective diameter < 15 nm we have observed a pronounced widening of the R(T) transition, which cannot be explained by conventional fluctuation models. For these ultra-narrow superconducting nanowires the zero state resistance is not reached even at T0. The effect is associated with quantum phase slip phenomena. Both effects have a universal validity and their assessment is crucial for further developments of nanoelectronics.
|Title of host publication||International Review of Physics|
|Publication status||Published - 2007|
|MoE publication type||A3 Book chapter|