Injection-detection experiments to study quasiparticle losses in Nb, using a series array of Nb/Al junctions

Gijsbertsen, J.G. and Flokstra, J. and Rogalla, H. (1996) Injection-detection experiments to study quasiparticle losses in Nb, using a series array of Nb/Al junctions. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 370 (1). pp. 75-77. ISSN 0168-9002

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Abstract:	Injection-detection experiments have been performed to study quasiparticle diffusion and quasiparticle losses in Nb strips using 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 simultaneously biased injector junction. For our sample geometry, the quasiparticle gas is described in terms of a one-dimensional diffusion model. It was found that trapping losses at the interface between the Nb base electrode and the anodised Nb2O5 dominate. In addition, a very low quasiparticle diffusion constant at 1 K, D = 1.2 × 10−4 m2/s has been found. We estimate that this corresponds to an electron mean free path of l ≈ 7 nm. Due to the difference between the bandgaps 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.
Item Type:	Article
Copyright:	© 1996 Elsevier Science
Faculty:	Science and Technology (TNW)
Research Group:	Low Temperatures - Biomagnetism (LT)
Link to this item:	http://purl.utwente.nl/publications/24441
Official URL:	http://dx.doi.org/10.1016/0168-9002(95)01054-8
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