Electronic Resource
[S.l.]
:
American Institute of Physics (AIP)
Journal of Applied Physics
80 (1996), S. 3923-3933
ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We present the results of injection-detection experiments that have been performed to study diffusion and losses of quasiparticles in Nb strips employing a series array of Nb/Al junctions. The I–V curve of the detector junction was measured as a function of the spacing between the (high-quality) detector junction and the bias point of the injector. For our sample geometry, the quasiparticle gas is described in terms of a one-dimensional diffusion model. The experiment shows that quasiparticle trapping losses at the interface between the Nb base electrode and the anodized Nb2O5 dominate. In addition, a very low quasiparticle diffusion constant at 1 K, D=1.2×10−4 m2 s−1, has been found. We estimate that this corresponds to an electron mean free path of l≈6.5 nm. Due to the difference between the band gaps of the base and top electrode and to the peak in the density of states at the gap edge, the excess detector current shows a characteristic voltage dependence for bias voltages below 0.5 mV. Theoretical lines for the excess I–V curves are calculated on the basis of a microscopic proximity effect model. All the features observed in the excess I–V curves are well described. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.363350
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