Low Temperature Physics: 42, 426 (2016); https://doi.org/10.1063/1.4951668
Tunneling into localized barrier states in superconducting heterostructures
V.Е. Shaternik1, А.P. Shapovalov1,2, А.V. Suvorov1, M.А. Skoryk1,3, and М.А. Belogolovskii1
1G.V. Kurdyumov Institute for Metal Physics National of the Sciences of Ukraine 36 Academician Vernadsky Blvd., UA-03680, Kiev-142, Ukraine
2V.Bakul Institute for Superhard materials NASU UKRAINE, 2 Avtozavodskaya Str., Kiev, 04074, Ukraine
3 NanoMedTech LLC,68 Antonovycha St, 03680, Kyiv, Ukraine
Received February 9,2016
Thin-film heterostructures consisting of supercon-ducting electrodes (molybdenum-rhenium alloy) and a nanoscaled silicon layer doped by tungsten have been designed and experimentally studied. Current-voltage characteristics of the junctions that for the first time exhibited local maxima on the current abrupt increase background were measured in the voltage range from –900 to 900 mV, and at temperatures from 4.2 to 8 K. The feature positions, symmetrical with respect to zero voltage, varied from sample to sample in the interval from 40 to 300 mV. With increasing temperature, they were washed out and completely disappeared with the disappearance of superconductivity in the electrodes. We relate the nature of the observed singularities to specific features of electron tunneling through localized in semiconducting barrier impurity states. The use of a superconducting electrode enhances the interaction between localized electrons and conduction ones due to square-root divergence in the density of electron states of a superconductor.
PACS: 73.21.La Quantum dots;
Key words: electron tunneling, heterostructures super-conductor–doped semiconductor–superconductor, localized states, Fermi-edge singularity.
Published online: March 23, 2016