Pa. Warburton et Mg. Blamire, QUASI-PARTICLE LIFETIMES IN EPITAXIAL NIOBIUM AND TANTALUM FILMS, IEEE transactions on applied superconductivity, 5(2), 1995, pp. 3022-3025
By using three-terminal double tunnel junction devices at 2.2K we have
injected quasiparticles into epitaxial thin films of niobium and tant
alum. The two junctions are coupled by quasiparticle diffusion and the
diffusion of recombination phonons through the sapphire substrate. A
comparison of our experimental results with a random walk simulation o
f the quasiparticle diffusion process enabled us to estimate the lifet
ime of the injected quasiparticles. The quasiparticle lifetime is not
recombination limited in epitaxial Nb and Ta films. Furthermore Ta is
less susceptible to the (as yet undetermined) loss mechanisms which go
vern the quasiparticle lifetime. This result indicates that tunnel jun
ction particle spectrometers utilising Ta absorbers may display better
energy resolution than those with Nb absorbers.