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Author Korneeva, Y. P.; Vodolazov, D. Y.; Semenov, A. V.; Florya, I. N.; Simonov, N.; Baeva, E.; Korneev, A. A.; Goltsman, G. N.; Klapwijk, T. M.
Title Optical single-photon detection in micrometer-scale NbN bridges Type Journal Article
Year 2018 Publication Phys. Rev. Applied Abbreviated Journal Phys. Rev. Applied
Volume 9 Issue 6 Pages (down) 064037 (1 to 13)
Keywords NbN SSPD, SNSPD
Abstract We demonstrate experimentally that single-photon detection can be achieved in micrometer-wide NbN bridges, with widths ranging from 0.53 to 5.15  μm and for photon wavelengths of 408 to 1550 nm. The microbridges are biased with a dc current close to the experimental critical current, which is estimated to be about 50% of the theoretically expected depairing current. These results offer an alternative to the standard superconducting single-photon detectors, based on nanometer-scale nanowires implemented in a long meandering structure. The results are consistent with improved theoretical modeling based on the theory of nonequilibrium superconductivity, including the vortex-assisted mechanism of initial dissipation.
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ISSN 2331-7019 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1303
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Author Gao, J. R.; Hajenius, M.; Tichelaar, F. D.; Klapwijk, T. M.; Voronov, B.; Grishin, E.; Gol’tsman, G.; Zorman, C. A.; Mehregany, M.
Title Monocrystalline NbN nanofilms on a 3C-SiC∕Si substrate Type Journal Article
Year 2007 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 91 Issue 6 Pages (down) 062504 (1 to 3)
Keywords NbN films, nanofilms
Abstract The authors have realized NbN (100) nanofilms on a 3C-SiC (100)/Si(100) substrate by dc reactive magnetron sputtering at 800°C. High-resolution transmission electron microscopy (HRTEM) is used to characterize the films, showing a monocrystalline structure and confirming epitaxial growth on the 3C-SiC layer. A film ranging in thickness from 3.4to4.1nm shows a superconducting transition temperature of 11.8K, which is the highest reported for NbN films of comparable thickness. The NbN nano-films on 3C-SiC offer a promising alternative to improve terahertz detectors. For comparison, NbN nanofilms grown directly on Si substrates are also studied by HRTEM.

The authors acknowledge S. V. Svetchnikov at National Centre for HRTEM at Delft, who prepared the specimens for HRTEM inspections. This work was supported by the EU through RadioNet and INTAS.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0003-6951 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1425
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Author Kooi, J. W.; Baselmans, J. J. A.; Hajenius, M.; Gao, J. R.; Klapwijk, T. M.; Dieleman, P.; Baryshev, A.; de Lange, G.
Title IF impedance and mixer gain of NbN hot electron bolometers Type Journal Article
Year 2007 Publication J. Appl. Phys. Abbreviated Journal
Volume 101 Issue 4 Pages (down) 044511
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Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number RPLAB @ s @ Serial 445
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Author Heslinga, D. R.; Shafranjuk, S. E.; van Kempen, H.; Klapwijk, T. M.
Title Observation of double-gap-edge Andreev reflection at Si/Nb interfaces by point-contact spectroscopy Type Journal Article
Year 1994 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume 49 Issue 15 Pages (down) 10484-10494
Keywords Nb, Si, Nb-Si, Nb/Si, Si/Nb, Andreev reflection, point-contact spectroscopy
Abstract Andreev reflection point-contact spectroscopy is performed on a bilayer consisting of 50-nm degenerately doped Si backed with Nb. Due to the short mean free path both injection into and transport across the Si layer are diffusive, in contrast to the ballistic conditions prevailing in clean metal layers. Nevertheless a large Andreev signal is observed in the point-contact characteristics, not reduced by elastic scattering in the Si layer or by interface scattering, but only limited by the transmission coefficient of the metal-semiconductor point contact. Two peaks in the Andreev reflection probability are visible, marking the values of the superconducting energy gap at the interface on the Nb and Si sides. This interpretation is supported by a method of solving the Bogolubov equations analytically using a simplified expression for the variation of the order parameter close to the interface. This observation enables a comparison with theoretical predictions of the gap discontinuity in the proximity effect. It is found that the widely used de Gennes model does not agree with the experimental data.
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Publisher American Physical Society Place of Publication Editor
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ISSN ISBN Medium
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Notes Approved no
Call Number Serial 1005
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Author Yang, Y.; Fedorov, G.; Shafranjuk, S. E.; Klapwijk, T. M.; Cooper, B. K.; Lewis, R. M.; Lobb, C. J.; Barbara, P.
Title Electronic transport and possible superconductivity at Van Hove singularities in carbon nanotubes Type Journal Article
Year 2015 Publication Nano Lett. Abbreviated Journal Nano Lett.
Volume 15 Issue 12 Pages (down) 7859-7866
Keywords carbon nanotubes, CNT, tunable superconductivity, van Hove singularities
Abstract Van Hove singularities (VHSs) are a hallmark of reduced dimensionality, leading to a divergent density of states in one and two dimensions and predictions of new electronic properties when the Fermi energy is close to these divergences. In carbon nanotubes, VHSs mark the onset of new subbands. They are elusive in standard electronic transport characterization measurements because they do not typically appear as notable features and therefore their effect on the nanotube conductance is largely unexplored. Here we report conductance measurements of carbon nanotubes where VHSs are clearly revealed by interference patterns of the electronic wave functions, showing both a sharp increase of quantum capacitance, and a sharp reduction of energy level spacing, consistent with an upsurge of density of states. At VHSs, we also measure an anomalous increase of conductance below a temperature of about 30 K. We argue that this transport feature is consistent with the formation of Cooper pairs in the nanotube.
Address Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
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ISSN 1530-6984 ISBN Medium
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Notes PMID:26506109; Suuplementary info (attached to pdf) DOI: 10.1021/acs.nanolett.5b02564 Approved no
Call Number Serial 1782
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